Be grateful you're seeing your FH for what he is before the wedding. Do you really want to marry someone who lets a 13 yo run his life for him and dictate all his choices? I certainly wouldn't. 

Why do you cancel outings for your kids if SD decides not to come? You should go anyway and let her have alone time with her father. Win-win. 

Agree with PP, go on day out with your kids. How old are all the other kids?

I would never have assumed the 13YO wanted to be a bridesmaid. 

Um, how about he tells HER that she needs to accept the fact that you are a part of his life and to stop being such a brat?

If he is not willing to parent her, you are going to be in a miserable marriage.

No way could I live like this, with a 13 year old dictating my relationship...and my life. Your kids don't deserve this crap, either.

I'm not one to jump to this but ... RUN. Your fiance already has a wife and it ain't you. it's a 13 year old tyrant. Do you really want the rest of your life not to mention your childrens' lives dictated to you by anyone else much less a child? 

You should have walked as soon as he would never answer your calls so as not to upset his precious snowflake. 

It's not too late, run  now. 

This little girl will never outgrow this behavior.  She is getting her way and your DH is making it worse.  Your life will be ran by a child and her BM.   I find it sad your children had to miss out on an outing because your SD didn’t want to go.  That would never happen.  I would have taken my kids and allowed your SO to stay home with his kids.  Stop lettting her dictate your life.  If you can’t even see your SO on weekends now,

it will only get worse after the wedding.   Think long and hard about how you want the rest of your life to be.  

I'm sorry you are going through this.  This must be agonizing.  I wish you and your kids peace.  Unless he changes something with his daughter, nothing will change.  Not sure what is really what you want to marry into.

You have invested 4 years with this man.  If this situation with his daughter is the ONLY mark in the "con" column then I would approach him with an ultimatum. 

"We need to go to pre-marital counseling to figure out how we will deal with your daughter.. or we won't be getting married"

Look, 13 is a horrid age.  She hates herself.. she hates everyone.. Everyone has it "better" than her.. WAHHH.

But, like you said.. she is completely dictating his life.  It also sounds like BM ramped up the crazy when she realized you were getting married to him.

He should be telling his daughter to "get a grip and I will not have my life dictated to me by a CHILD.. I am your FATHER and it is MY choice who I marry.  You have given us ZERO reasons why you all of a sudden have a problem with my Fiance.. You either cut this crap out.. or you will have some very serious consequences to suffer.. and if I lose my relationship because she can't deal with you being a brat.. I will have plenty of EXTRA time to deal with your consequences.. GET IT?"

he says I need to accept the way she is, he won’t give her boundaries as her mother kicks off at him. 

This is also a big problem, he is afraid of BM.

Run! I am not kidding....pack your bags and run now!

Even when the kids are grown....you will have resentment from what is going on now. I know that is where I am headed.

For the first year or so of mine and DH's relationship....he wouldn't answer my calls or text me if he was with the kids....not b/c they were busy but b/c he was afraid of them reporting back to BM. He couldn't hug or kiss me good bye in front of them for a good 2 years and only recently....since we had a baby a year ago... (after being married for going on 3 years) stopped looking over his shoulder to see if his kids were looking before he would hug or kiss me hello or good bye. Some of that stuff you can never get over......

Your SO (like mine) is afraid of BM and afraid of SD....that will NOT change. Can you live with it? It is a shitty life, I promise you! I would never ever do this again.

Her being difficult at 13 is not the issue - him letting her run his life, and his fear of BM are the REAL issues.  Please do make sure those are addressed before you get married. 

You have an SO problem! SD is acting this way probably because she was raised to believe that she is on an elevated parent/parent level with SO. Not a parent/child level. If you want things to get better SO is going to need to step up and be a parent to SD and not her whipping boy.

Darlin' this guy can't be that wonderful if he's catering to his daughter and you're only an after thought. This girl runs him and what he does and when he does it.  I bet he hasn't even called her out on the whole apology nonsense that she can't even give examples on.....

I don’t see my FH at weekends, he doesn’t mix with my family because SD gets upset,

You don't see him on weekends and he's perfectly ok with this? What happens next, he'll need permission to be in bed with you? What happens if you both decide to have children? She gets a say in that too?

I'm afraid he already has a wife and it isn't you. Please reconsider marrying this man because you will never be a priority to him.

No, no, no, no, no.  This is not a man. This is SD's little bitch.  He is not an equity life partner for you or anyone else for that matter. Except for his crotch dropping.

Please do not pollute your life with this waste of testosterone and his shallow and polluted gene pool.  Protect yourself and your children from them all by purging them from your life.

Most disgusting is that there is no mention of his other child.  Has he sacrificed that kid to the toxic POS SD?

Congratulations on the end of this relationship.  It should have never progressed past the first load of crap delivered by his toxic crotch turd IMHO.  What could possibly be even remotely wonderful about a ball-less non man who not only tolerates but enables this POS kid to destroy the lives of 7 people who would otherwise be a family?

Do not lament the demise of this trainwreck of a relationship. Celebrate it.

Based on what you've written, cancelling the wedding is probably the best thing you can do.  Your SO needs to make a lot of changes before he can even start to be a spouse worth having.

I am sorry that you feel awful, sad, maybe angry, about canceling your wedding. IT Hurts (HUGS)

Frankly I tip my hat to you for realizing this union, although he is your dream man, will not start off on the right foot. Certainly your parents, if they are living must feel relieved too.

Your bio kids deserve to grow UP in their home without all this drama with boyfriends daughter.. I would suggest either moving out with your kids OR giving their bio dad custody until you can move out. 

Just something to consider.

PLEASE don't run off of Step talk---stick around, there are a lot of younger single girls who need to hear your story. They tend to have magical thinking..

goodluck

Cancel the wedding or you'll never spend time with him on the weekends (and most likely vacations). Your fiance has been trained to ignore you to spend time with SD. If you marry him, there will suddenly be lots of reasons for SD to want to spend time with dad and he'll jump at every one of them. Your marriage will be controlled by SD (just as much, or more than, your dating time has been)

He won’t tell her to grow the eff upp and be respectful/civil, because then she’ll chuck a manipulative hissy fit because after all who do you think she learnt it from? Yup bio mum who is more than likely a hcgubm, narcissistic and manipulative and thats how she has treated your fiance which is why he is terrified of her.

i don’t go out with skids but when they would all go on and on about their bio mum and stepdad and try to make it i wasn’t there, my husband would involve me in conversations to show i was relevant.

Your fiance not answering phone calls because it’ll upset sd13 is telling her she is the centre of his universe and she will amp up the hostility.. any man who has the nerve to tell his fiancee that “i refuse to lay boundaries with her, you have to accept her for who and what she is” has told you he will let her boss everyone around, she will and is already calling the shots, she will be allowed/enabled and encouraged to treat you and your kids with hostility and disrespect and will be excused for these actions because your fiance has no balls

he has told you he does not respect or value one bit and frankly speaking, he’s a selfish piece of shit to actually bring you into his life like this and your kids. He’s after the image of a one big happy family like he’s an amazing family man when reality is he is a shit parent...

there are good men out there who wouldn’t allow you to be treated this way. I’ve been married to hubby just over 4.5 yrs and knew his about 1.5 yrs prior to that, i want nothing to do with his kids, they are not family abd have never treated our kids like family but because they are pathetic failure to launch, they like to play glorified best bigger siblings ever but hubbies family see right through it

don’t let love cloud your judgement... why allow your kids to be in this toxic unhealthy depressing environment. If this future sd13 is to the max she may even push things as far as getting your man (her dad) to do bra straps for her bikini or parade herself sexily just to piss you off and show she is competition 

FH is the problem here, not SD. He allows this, he allows himself to be bullied by a 13 year old, he allows a 13 year old dictate his life

This is a crucial time for you. You can do the hard work now, or do it later, but you're going to have to do it and you have more leverage now than you will after you marry. I'd tell you to delay the wedding, but I realize that's easier said than done.

I had similar issues with my SD before we married. My husband assured me SD was happy for us, and in spite of all the evidence that she hated me, I didn't address the issue before our wedding.

Then I got married and was stuck. I saw suddenly just how bad SD was. I saw that my husband, like yours, was happy to accommodate anything SD wanted and it was as if I wasn't even a consideration. There was no honeymoon phase...it was all fighting about SD for years.

What a shitty way to start a marriage. I thought we might split up. Now when I remember what should have been happy days, all I think about is how SD was already pulling all the strings between my husband and me.

Don't let this unfinished business ruin your big day and years of your marriage. If I had to do over, I'd get into serious therapy right now -- daily if you need it until the wedding -- to figure out whether you and he have any hope of compromising to solve the SD problem. You aren't necessarily looking for a quick fix before the wedding (that's too tall an order) -- just go see if he's at all willing to budge on SD issues to resolve this with you. Just see if you and he have the tools to resolve major conflict because nothing will be bigger than skid issues and you already know you're going to have to resolve them. 

Tell the therapist the situation and the time limitation (6 wks), and that you're hoping to have a solid plan to tackle this before you marry. Tell the therapist you'd rather know about a stalemate BEFORE you marry, so you're hoping he/she can give you an honest assessment on how you and he problem solve -- are you actually ready for marriage? Ask the question now. If your husband-to-be is unwilling to budge in those therapy sessions, you know the marriage will be that much harder -- but it's something you should know going into it, not after it.

I admit, hours of therapy leading up to your wedding doesn't seem very romantic. Neither is worrying about caterers and unity candles, but you probably did it so one day can be perfect. This is really the kindest thing you can do for your marriage or for yourself, if that's how it ends up going. You will feel better going to that altar if you've already made some progress on this. Otherwise, it will just feel that much more uncertain going into it.

This will never work out. Unless your SO deals with his DD before you get married.  You have to Waite a year or two so DD get dealt with. 

If you think the issues are big now with SD, just wait marriage will make it worse. Your DH has a wife already, and at 13 to have this power just wait until she is 23, 33, onward. TOTAL NIGHTMARE!

You will have your self esteem plummet, any respect for DH will be completely gone, not to mention your children will suffer, because they have a stressed out mother and will notice the special treatment the princess gets.

I too thought that after marriage things would get better with SD. It didnt.  It will sicken you to watch your spineless DH cater to this self centered princess.  You will never have a moment of peace. Resentment will grow, and the happy person you once were will be no more. Think of all the apologies you will be forced to make to the royal brat to keep the peace. Your apology (for nothing!) will never be enough. That in itself is humiliating. Obviously your FDH wants you to "suck it up" ...

Engagements get broken all the time. Better now, than be in a lonely stressful marriage. This is not the man for you. He is already spoken for.

Please do not get married right now. Until you see your fiance better handle his teen daughter, you do not want to committ yourself to this situation. She's 13, and if her father doesn't tell her to knock it off and mean it, you are in for at a minimum 5 years of hell. And it won't end just because she's 18...

It might be painful to cancel the wedding... I get it. But going through an annullment or divorce will be worse.