Need advice warning can be triggering

My husband and I will have been married for two years this Valentine’s Day. We dated for only three months before getting married which I know was extremely fast I’ve never moved that fast with anyone , but at the time I had zero doubts he was the one. He was caring , supportive , appeared to be a great father and hard working he checked all the boxes. We even did marriage counseling the 3rd month before we got married. We didn’t have sex before we got married either. Once we said “I do” everything changed he lied to me about his finances and was actually 20,000 in debt, he actually was this great father he pretended to be while we were dating and honestly I don’t think he was really over everything from the last marriage because we have gone through a lot because of it. My biggest problem now is the children and his ex wife. Before we got married we had two children a piece from our previous relationships. Our kids are very close in age I had a 5 yr old boy and 3yr old girl and he had a 7yr old boy and 5 ye old girl who are now all two years older and we have welcome one of our own who just turned 1. After we got married he and his two kids moved into my home home. His ex wife did not like that she’s very controversial and just a nasty person as well as her boyfriend. His ex wife cheated on my now husband when they were married with her current boyfriend after they got divorced she moved her boyfriend straight in and they have been together ever since. Her boyfriend has 6 children with three Babymamas and none of them allow their children around either of them. The first incident to happen once we moved in together was with the ex wife. She kept telling the kids that she was going to fight me and I talked to her about it she lied to my face and the kept doing it. The next incident their son spit in my sons face and told my children they were not sibling because my son is black and he is white. The next incident was me waking up to his son holding a knife in his hands stabbing my walls kitchen chairs and more thank God nothing happens to the other children. Now with this last incident I have no idea if we can stay married I found out his son who is 8 has been molesting my 7 year old son and my 5 year old daughter his son has been removed from my house since we found out this happened and now I didn’t see how we can ever go back to a normal family dynamic. Everyone I try to work through one issue the next arises a