Well this is my first post and I did not know what else to do....here is the story and ill post my question at te end.

BF and I been dating for 7 months then we have been official for about a year and a half. I moved in with my BD, we have been here for 9months. As soon as we moved in BF started asking me to help im sometimes with picking up SS from school. Then it turned into dropping him off and picking him up, then it was and everyday thing up until today. Before SS mom would have him week on and week off. Then it turned into BM calling us more and more to keep SS and now we have him all the time because BF is worried about how he is taken care of at BMs house. She has a lot of personal issues and cant be a mother right now to SS. But she wants to pick and choose when she decides she wants to see SS and that makes SS extra emotional on top of his ADD because he keeps aking why he cant stay at BMs house like he use to. SS is eight by the way. So I was patient with SS and his ADD and his parents splitting up, knowing it is hard to accept and deal with. But these last couple of months have been HELL. BM keeps telling SS that he doesnt have to listen to me because I am in her place and I shouldnt be here and to basically disrespect me and my BD, to lie to BF about what goes on at her house (she has a alcohol and drug problem with a BF who is in and out of jail, thats why SS is at our house now) He treats and speaks to BF like CRAP! tells him he hates him and he wished his mom married another man and had him with that man. And all this hate talk is over BF telling him to eat dinner or clean his room. Then SS continues to say his mom is better than our house and he hates us. This is over EVERYTHING and EVERYDAY! So if I tell SS to do something or he hears no from my mouth, an all out tantrum will happen or he will acknowledge my command or response and still do as he pleases. He constantly messes with BD who is three, and says we always take her side. He will only play with her if she has something he wants, he manipulates her and everyone else. When she wants to play he screams in her face telling her to get away and e doesnt want her in his life. I get upset at this. BF tries to talk to him but still nothing changes. BF wants me to be a SAHM and I want to work. But now BF is upset and giving me the cold shoulder because I told him I cant handle his son with his mom making it harder for me. I refuse to watch him any longer until the behavior changes. Im just too stressed out and it got to the point where I hate being around SS. I dont want it to be this way but im human and have feelings too! and on top of all this I have to deal with my own child custody issues and crazy ex! But I feel I was tricked into this relationship because I told him everything about my ex when we first dated. He didnt tell me they were still married but seperated and barely said anything about the type of mother the BM is and her role as a parent. I found all this out myself after I developed feelings for BF and BD sarted warming up to him. Now I dont know what to do because I want to be with BF but I dont think I can handle all this drama. Now its worse because he is giving me the cold shoulder since I stated my concerns and feelings and not wanting to watch his son right now. BF works tweleve hours a day and thats a lot to deal with alone!! So my question is am I wrong for saying to BF I refuse to keep an eye on SS? Why is he mad at me? I would never put him in a position like this......