Yep, ignore her and it is what it is. Disengage. Not your kid, not your problem. You married your husband for him, not her. 

Why doesn't matter. What matters is the what... that she is doing.  Meet her new perpsective with escalating unpleasant consequences until her behavior improves and don't worry about why she is chosing to be a "B".

No money, cut off her phone, no contact means no support.

I wouldn't waste your mental energy on trying to figure out the whys of your adult SKID's behaviour.   I would treat with courtesy but coolness when you meet them. 

I agree with the replies above, but do understand that when an adult skid does this to you, it is really hurtful. Try to disengage now, I have wasted almost a year feeling hurt, confused and angry by a similar reaction. You aren't going to be able to change it, and stressing about it is only hurting you.  

Disengagement is not the perfect answer but it it the best answer when dealing with hostile skids.  There are several 'degrees' of disengagement.

You may want to just back off and treat her as if she is a coworker you don't like.  Don't initiate conversations with her.  If she asks for anything tell her to ask DH.  if DH is like mine he will weasel out of setting her straight or demonstrating to her that your marriage is his top priority.  In this case, don't bring SD up in conversation, if DH brings her up, just say, "Hmm" and change the subject.  Don't pay for anything or clean up after her.  Let DH do it all. 

You may develop an approach somewhere between being evasive or banning her from your home.  Whatever you do, set up boundaries for SD and DH, and stand firmly by them.  After all, you know by now that you really have a problem with your DH if he has not taken any action to set SD straight.

I endured this B.S. for 20 years.  SD was vicious, selfish and hostile.  DH refused to show her that we were a united couple.  They were a real team at belittling me.  She finally had a meltdown and DH ran out the door.  I gave him the choice of working on the marriage or leaving.  SD was also banned from my house (which I owned).  DH can visit her just about whenever he wants but SD is no longer welcome in our home.  I have not seen her in over 8 years and it has been a blessing.

Hi there Country! Welcome!

SD is just one letter off from STD. (Coincidence? Disease?) Just an observation.

I have been through that phase, and it is baffling. Because we tend to be caring people, we long to know the "why" of things. I am a solution focused person, so I spend time trying to rationalize it, decypher it, make sense of it, whatever you want to call it. Like someone else mentioned above, she's "wasted a year." And I can empathize. Letting your mental merry-go-round turn day in and day out on this will wear you out.

If she and her father are so close, who knows? Maybe your DH like mine and others here, talks behind your back to stir the drama, and to maintain that cohesiveness (mini-wife, "daughter you are first with me always" mentality)That is known as "triangulation." It has huge ramifications and can be very damaging. There is a reason "why" but you need to decide if it really matters, hurtful as it may be. Sometimes what we don't know CAN hurt us, and sometimes what we don't know is SELF-PRESERVATION in disguise.

If things are good with your DH, then thank your lucky stars you don't have to play her games. I was releived when this happened to me. For a while SD would "group text" DH and myself, (and sometimes others as well)almost as if she were keeping record, or to say, "See daddddeeee? I'm playing nicely."

Sandye21 is a veteran at all the chaotic drama caused by these mini-wives, and their daddeees who refuse to man up and take a stand for their marriages. I pray that's not where you're at, but as she mentioned disengagement moves in stages, as do these baffling relationships we are all a part of.

Best of luck, and keep us in the loop! We are here for you and for each other.

I have been through this phase with my OSD and yes it's very hurtful, and this 'phase' has never really ended!

I see no harm in calmly asking her if everything is okay with the two of you, that you care about her too and if she's upset with you for some reason would it help to discuss?

If she blows you off, then it's on her, at least you tried

It does help to know why, and once I learned that my SD's seemingly sudden change from loving the ground I walked on to hating everything about me had everything to do with her own jealous insecurities about me/my relationship with DH, and not in fact anything at all that I had done, it did make it easier to swallow (not that it wasn't still an extremely difficult and frustrating situation)

If you and your SD had a great relationship, and you have done nothing different, and can't think of a thing you possibly could have done wrong then most likely the issue is with her and something she's struggling with

There tends to be so much jealousy in these step-relationships sadly...either a skid who is jealous of the step-parent, or a step-parent feeling jealous and resentful of the skid 

And when there's jealousy to contend with, it doesn't matter how great the SM, the skid will hate her - sometimes even more for it. And same goes when SM is jealous of their skid

With my OSD, I literally fell over backward for many years trying to please her and win her over. The harder I tired the nastier she got. It took me a long while to figure out that she simply did not want a good relationship, or any relationship, with me. She was so jealous and insecure and resentful of everything about me, and so bent on revenge that the more I tired with her the more pleasure she took in hurting and humiliating me. She wanted me to know that no we were not friends, no she did not like me or consider me family, and the nicer I was to her the more she would drive the message home that this war, I was the enemy and she would win at all costs

Once I realized all this, I also realized that trying to work with her was futile. That the best course of action was simply to stop trying. She was just bad energy for me. I learned to smile and wave, ignore and move above it. Focused instead on being around people who made me feel happy not awful

Now her behaviour has very little impact on me or my life, and I think she knows it

I got her message loud and clear and have fully respected her choice in life

Give your SD the opportunity to repair the damage she's creating in your relationship, but once you've given your all and she has made it clear she's not interested, then respect her wish and go live your life surrounded by the people deserving of you