She's here because she gets some kind of pleasure from kicking those who are already down.

You may not have the great nice house you have now...but you will find happiness and that is worth so much more! Your boys will have a happy mom instead of a depressed, beaten down mom. I understand, I have a great house and it has made me think twice before separating from my husband when he gets in his verbally abusive rages (he is working on that). I bet you can get a smaller house and slowly over the years invest in it and it will make you very happy.

Megan - so sorry this is happening to you. It sounds to me like your DH is "replacing" your role i.e. wife - with his DD. They are doing things together, colluding, he sides with her and allows her to behave disrespectfully.

Seems to me YOU did the right in terms of making a stand with your own children and how you showed them they needed to behave with your DH. That was being a good wife and mother. Sadly, your DH is allowing his guilt over being sort of absent from his DD's 24/7 life, her experiences with her BM's bf and his joy at finally having her *home* in his eyes to guide how he treats her and everyone else. Lets look at it this way, if you favour one person in a household and treat the others like crap, then there are going to be fireworks, hurt and anger. This is what is happening, however to compound that hurt and betrayal your DH is trying to turn this around onto you and make YOU the issue. As after all both DH and sd are getting what they want atm, validation from one another (and they are being emotionally incesteous), therefore they will resist any and all attempts to see reason. It's called denial, living in a fantasy and their world is VERY dysfunctional and unhealthy.

You would not be rational nor healthy if you allowed this to continue and by this I mean accepting it, continue trying while everyone else is not accountable and in fact they are doing the opposite of trying. STOP.

The reason your DH is seemingly calm even though you both have agreed to divorce is potentially down to a number of reasons - 1) he doesn't think it will happen and is using the fact you have slapped him as blackmail (btw I do not condone violence however tbh you have been living in a pressure cooker and your DH will purposely attempt to push your buttons in order for you to lose the moral high ground so he has ammo to use to blackmail you into submission and under his control - do NOT lose control with him again) 2) he is using sd has an emotional crutch and a surrogate wife (see above where I mention he is replacing you with her minus the sex) and therefore doesn't feel the lose like you because your role is already filled - by sd.

I do believe your DH is to blame here mainly as HE is your husband, sd doesn't own you any allegiance except for common courtesy and respect. That said, sd IS 18. She is not a little girl and while she obviously has issues, these should NOT be pushed onto you. Having issues and finding an innocent target for these should not be accepted - sorry. I have issues but the responsible and loving thing family should do is point those issues out, try and help but that does not include making excuses for shitty behaviour and blaming the person who is the target and eventually gets sick of being unwilling dragged into that person's problems.

What YOU need to do is pick up your big girl panties and paste that fake arse smile on your face and not allow those two A holes to bother you. The more you show your hurt, the more they both will be crowing. Sd because she will love the power and the fact daddykins has sided with her and DH because ofcourse you are in the wrong and its good you feel hurt as you should be punished for your horrible crimes against him and precious. DO NOT SHOW THEM HOW UNHAPPY YOU ARE.

While inside you may be dying, please give yourself a stern talking to. Your husband is not acting like a husband. Instead he is acting like he is having an emotional affair with his grown daughter. The fact he has genuine regrets over the past with his DD does NOT excuse breaking his wedding vows. F*ck no. It's time you realise that ok, you slipped up by slapping him but what this guy has done is worse. You have had 6 months worth of pain and all because he refuses to BE a husband. He was absent from that role as soon as SD walked through your door. HIS fault.

Personally I would do this. Any time you have to talk to DH, talk to him like a distant business colleague. Polite, at arms length however do so positively (make this man REGRET ever killing your marriage and acting like the sweet person you are VS the shrew that he's created will KILL him more). Do NOT get drawn into discussions about sd. Nothing needs to be said, even if you head if chock full of WTF is happening and hurt. As guess what?!! DH WILL NEVER listen. He will take anything you say as an attack, he will turn it around, he will use it as an opportunity to attack you, to accuse you of things (all which serves to destroy your confidence and make you feel like its your fault - so not give him this opportunity). He may also use it to negotiate and blackmail you - no deal imo. If he decides to start on you, your marriage, then have a set response "I have told you how I feel about this situation. You have gone ahead in the last 6 months and made whatever decisions you felt necessary regarding our marriage, our household and sd. The consequence of which is I now have made my own decisions - I am no longer accepting it." If he's abusive "that is not nice. I am not listening to this." Then walk away.

Your DH may look to TRY and make you react so he can get that control back over you. He may escalate his behaviour and that may include subjecting you to longer silent treatment and ignorance. Well look at it this way - if they both are ignoring you, this means you are not being abused, mistreated. Instead you are having peace. So be happy about that. Use the time for the following:

1) Get legal advice - even if you do not end up divorcing, info is power and you do not have to let DH know you have gotten advice unless it necessary to blow any threats he makes to smithereens.
2) Use this time to go have some fun - recruit your galfriends/family and go shopping, see friends, have dinner, have them over for a BBQ (DH may find this uncomfortable which is GREAT, after all both he and sd do not care if you are squirming). While you are having fun, paste a smile on and be happy. Showing DH what he is missing is the best form of revenge and will KILL sd to see you do not give a shit on the outside. If DH accuses you of enjoying your marriage ending "I am just getting on with my life DH, just like you and sd are. After all wasn't that you and sd giggling in the living room last night, the night before?" Then walk away.
3) Go get a new hairstyle. May seem cliche, but you need to boost your confidence and show DH you are not going to fall apart from the fact he doesn't want you. So what? You can do better, so SHOW him that. It will annoy the hell out of him.

Do all of the above with grace and class. Do not raise your voice to sd or DH. If sd is a bitch to you, do NOT ignore it. You now have nothing left to lose (however hide any and everything worth of value to you) and just do not put up with her nonsense. Do so politely but coldly. DH doesn't like it? So what? What's he going to do? Divorce you? Ha!! He has NO power over you now. Feel liberated and use that power to your advantage.

Good luck.

He does NOT need to take care of SD...she is an adult! Maybe you should point that out to him...if he was my DH, the conversation would go like this:

"Were you happy 6 months ago (or whenever before SD moved in)? Six months ago, would you have let SD move in if you knew it would cause a divorce? Why are you letting that happen now? Why are you letting a grown ass adult ruin our relationship? Where do you think she will be in five years? Because I think she will be married and starting her own family and you will be all alone wishing for the family you had six months ago. Why don't you pull your head out of your ass and see this situation for what it is? Your daughter does not need you to provide for her anymore...your daughter needs you to teach her responsibility so she can survive on her own in this world. You are choosing another grown ass adult woman over me. A woman that will drop you like a hot potato once a young man sweeps her off her feet. She can leave you for another man...why can't you leave her for the woman you ARE MARRIED TO?"