This is a difficult scenario, I am trying to get my head round the facts. As I understand it from this thread, you met DH, you owned your house, he was bankrupt. He was trying to gain sole custody of his DC, which you knew and approved of. He failed to get custody, but DH remained an involved Dad. When ex wife had breakdown you agreed for them to live with you. However their teenage behaviour and your husband not supporting you means you hate your stepchildren.
You are angry and resentful, want to vent and get defensive at any advice, telling others to f*ck off and back off.
You have made clear that you went into this marriage with open eyes. You knew of the DC but didn't expect to live with them. Unfortunately circumstances have changed and you now need to deal with the consequences.
Having waited until 44 to get married, clearly you were used to a fair degree of autonomy, but now you don't have those freedoms. I can understand you feel frustrated. This makes you angry and resentful.
This is not the DCs fault. It is however the responsibility of you and you DH, as the adults in this scenario, to make the best of your current circumstances
You need to accept some of the generous and kind advice you've been given here ( and I am not being sarcastic, there has been plenty of useful advice other than LTB)
Discuss the situation calmly with your husband, set clear parameters of acceptable behaviour of ALL of you, including you. Consider how difficult this is from DC POV and you DH POV. Learn to deal with your resentment.
If you cannot get over your resentment then sadly you will need to plan your exit strategy. No equity, dog or not, you need to resolve this.