my mom and step dad divorced?

[Brittey]

Well my step dad left my mom for a married women and she kicked her husband out then the husband for out under law he can still live in the house. Well that didnt go over to well with my step dad so he moved back in here and i really dont like him! and my mom promised me nothing would happen and that we are trying to find another house to move into. Well i have a 2 1/2year old brother who wouldnt sleep last night too scared his daddy was going to leave so my brother told him that he couldnt sleep on the couch or in his bed which that where my step dad was supposed to be sleeping in my brothers full size bed. So my brother got up and came into my room and i took him back to my moms that wheres hes been sleeping and i walk in there and my mom and step dad are sleeping in the same bed i flipped out and i told them that i was moving out to my grandmother house and i was done with them. This is like the 9th time he has left my mom and has came back but my mom saids she not taking him back
but i dont believe her because she says that everytime. In less then 3mths i will be 18 and i told her if she did i would take my brother away from her and disown her because he shouldnt have to go threw what i went there they were married 14years. So how do i tell her that intill we move i dont want to live with her because im not dealing with this. so i didnt sleep all night up all night crying and now im going to school with puffy eyes what a great day its going to be might pretend to be sick and not go! Their are already in counseling for my brother because hes an angry child and they said he needed it and i have no clue what to do other then cry to my boyfriend at 3am!