All of this is awful. But since he held your son under the water "as a joke" tells me all I need to know. That is abuse. You need to GET OUT OF THERE and protect your son. He is in a terrible environment.

Seriously. Get out NOW.

Perhaps you might try some counseling on your own. You might find it helpful to spill all this out to a professional that could give you honest opinion of success or failure of anything ever changing in your household.

At some point you may have to take into consideration as to all this affects your own children. Pulling knives on each other? What kind of home life are you willing to subject your own children to in order to stay with this man you claim to love so much. so far, all the love in the world you have to give to this relationship hasn't been enough to overcome the problems in the home. 

Do you move across country to move in and start this relationship? I ask because you stated if you left you'd have to go back to your home state. Admitting this relationship isn't working is not being a failure. You had no idea when you moved to live with this man and his children that there was all this dysfunction and potentially unsafe living quarters for you and your children. You know now. You've given it time and a chance to improve. It's not. That's not failure on your part. 

There is nothing to be ashamed nor embarrassed about leaving a relationship that is unhealthy and dangerous for you and your children. It doesn't mean you failed. It means you loved yourself and your children enough to get the h*ll out of a very bad situation. That's not a bad thing, It's a good thing. Some counseling for your own sake may help you realize this and give you the strength to do what is right for you and your children. 

These kids sound very disturbed. You have a DH problem though. This is total BS! "My guy thinks I am too hard on his kids, and they aren't used to rules or being asked to do chores, and I shouldn't expect so much out of all of them". You should tell your DH that having rules and boundaries and doing chores prepares kids for adulthood and teaches them to be respectful and learn how to be responsible. I thought I had it bad but you seem to have it worst than me. Please talk to your DH or get out while you can.

Moving out is the best thing you can do for your son...and yourself. It is not failure. Failure would be knowing what this is doing to your health and to your son and doing nothing about it.

Firstly, you cannot expect the children to be anything better than what they are based off their parenting. You can't expect them to be walking saints when they've been conditioned from their environment for a decade already. Let's take the rest by paragraphs because you do have a lot to get through:

P2: This goes back to my first statement, your SO does not prioritize his own mental health so obviously his kids don't either. When kids grow up in disfunction for so long they accept it as normal. The only way to make the change their perspective is to SHOW them the difference. Bring them around other stepsiblings who love each other and get along, who display manners and sharing...SHOW them what happens to children who don't share, who hate, and hurt one another (juvie, jail, prison, etc). The most relief I ever got in this role as stepparent was understanding that I cannot care/do more for the kids than their own parents. You have two who refuse to accept their own flaws so how can they see how its affecting their children?

P3:  Have you ever had them describe themselves and their personality traits out loud? Have you tried putting on a movie and pointing out the bratty behavior of the kids on TV or the good behaivor you see from other kids in the store? Kids will reflect accordingly. All humans want to be accepted, thats basic human desire so your SO needs to sit them down and point out that they need some behavior adjustments or people are not going to want them around.

P4: The girl...easy enough. Her currency is her phone. Take the phone (because yall are the adults and she is a child) and give it back to her once she has showered and done a few things around the house like loading the dishwasher and straightening up her room then she can go hog wild on her phone for the rest of the day. Phones are priveleges that entitled children assume as needs. Nope. Be consistent and do this every single morning without giving in or skipping (showers) because if you give in once then you break the habit. 

P5: The boys relationship with his mom is something you can't fix. All you can do is make it crystal clear that it is below standard and not acceptible in your house. Pulling knives? You call the cops for that and make him suffer natrual consequences...something the adults in his life seems to keep him and his sibling from. He will do it again because he hasn't been taught it's not acceptible. Hopefully its not at school or on another student/child so he can go to jail before he hits his twenties. You can teach him now, or someone else who is a lot less forgiving will teach him. 

Skipping paragraphs down to BM: Ignore her. She doesn't need or have to speak to you about anything. And do you really honestly think anything good would come from it? It won't. They will always find conflict, they will always deflect on to you so stay out of it. If your SO wants the constant phone calls and messages to stop then he needs to set up boundaries  and enforce them.  No longer accept calls or text unless its for BM to speak directly to the kids. Any other communication should be strictly about the kids and through Email or some other form of recordable communication (our family wizard is another good one). He needs to "Ignore the whore" when she comes at him with conflict, drama and pointless conversation. When they text him manipulating him about BM and her household he needs to call them out on it each and every time. He needs to say "well you say the same thing about me and my household when you get mad over here so you probably just need to cool down and talk to your mom about whats bothering you instead of trying to run away" This guy and his ex are letting these kids play these games and it won't stop until HE starts giving boundaries and consequesnce to all three fo them. Your liife won't get better until he choses to change as a parent. Most of the time it is easier to separate and cut your loses because most people don't change...

Are complete deal-breakers. Get out  now, before you get pregnant (or worse, married) with this dysfuntion. It will only get worse, it will definitely not get better. Take your loving, lovely child, and focus your energies and attention on HIM, not those disturbed, cretins,your financial resources on HIM, not those ungrateful brats and parents. SERIOUSLY.

If you have a question on what I consider deal-breakers:

1. Your SO will not back you up on anything at all. Pulling a knife on someone at 11, and its poo pooed. holding someones head under water, and its "mentioned, then ignored". Thats going to get worse.

2. You always being the bad guy, because you require rules, consistency, polite behavior and cleanliness. That gets worse in teenage years too.

3. Mental Illness. You do not need to get pregnant from this dude. And your child does not need to be around this either.

4. Needy Ex. He needs to set boundaries with her and cut her off. That will get wrose unless you set boundaries with HIM.

Honestly, get out while you still can. I think you know this in your heart, you just need to hear it read it see it. You are ot a failure if you leave, you WILL fail if you do not. Let them figure it out for themselves, let them get the therapy they need on their own, just get out.

Why exactly are you in love with a "man" who is is an abject parental failure and waste of parental skin?  You need to get your child out of this toxic environment ..... NOW!!!

If I were your nearly drowned 9yo I would take a bat to this asshole's shins and give him a life long lesson and limp to never fuck with me again.  The only way to deal with a bully is to beat the bully's ass and  your 9yo needs to apply that resolution methodology in dealing with the children of his mother's poor choice of partner.

I was a very laid back mellow kid.  Once I reached the late Elementary School and Jr. High age bracket the bullies started targeting me.  I hated fighting. I don't care much for pain. So I didn't fight back and I pretty much blew them off... until .... I finally realized that getting hit hurts whether I was fighting back or not. So I started fighting back. Not only fighting back but being exceptionally brutal when I did fight back. I was never a bully but once I had my epiphany I made sure that they hurt as much or more than I did.

One had a crushed hand, one had scars from reconstructive facial surgery where his lower lip had to be repaired from the tip of his chin all the way to his bottom teeth and several likely couldn't father children.  All from three incidents and three incidents only.  It only takes standing up to a bully once (per location) for the local kid and bully community to get the message not to mess with that person.

From K through second grade my son was the target of a bully on his school bus.  This weasle of a bully escalated his targeting of my son to the point that my son had bruises on his neck from this kid choking him from behind on the bus every day.  We reported it to the Principal, the bus company, etc... to no avail. So... I taught my son how to deal with it. The bully was 3 years older than my son though not a large kid. My son, like me was mellow and completely non confrontational. 

On the last evening that my kid was this bully's victim I pulled two chairs to our living room, one in front of the other, and put my son in the back chair while I took the front.  I instructed my son to put his hands around my neck and choke me.   He started crying. The bully had so tramatized my 7yo that just putting  his  hands around my neck had h im sobbing.  So I showed him what to do. We switched places, i planced my hands around his neck and instructed him to grab my ear.  Then I instructed him that when the kid choked him on the bus the next day to grab the bully's ear as hard as he could and rip his ear off of his head. And my son did.  At least about half way off of his head.  We got called to the school the next day, the Principal and police were there, I showed them the several layers of neck bruises from the bully choking my son, the incident went away because there was a record of our complaints.  That evening there was a knock on our door and there stood the father of the bully, the bully with his head wrapped like a mummy was standing behind him, and the father tried to hand me the hospital bill. I called my son to the door and showed the father the bruises, explained that his kid was in 5th grade and mine was in 2nd and he could shove the hospital bill up his ass and closed the door.  He grabbed his 5th grader by the back of the collar and kicked him in the butt every 2nd or 3rd step they took down the street to their house.

No more bullying.

Your son can stop the bullying.  SS-11 should not like how your son teaches that lesson.

Or better yet, you and your son put this shallow and polluted gene pool fading in your rear view mirror as you move on.