Step dad hates my dad & me

So my step dad has been in my life since I was eight years of age and he pretends to like me to my mom but behind her back when I was 16 and hed lock me in my room because hed say something to make me get in trouble and grounded he took my tv and cell phone made me wait in my room till my mom got home.. and he told me I make his life miserble hes here for my mom not me then cheated on my mother … And she still takes his side over me do I not matter… I am now 18 and having a child with my boyfriend and he wanted my dog to live with us and now that he jumps into my convo and I said something mean he throws my dog out and tells my mom he doesnt want it inside and my mom said well it could be inside and he goes and says just listen to me nadine aka my mothers name … Now to my dad he always tried to rub it in his face that he didnt have me and that he did and he said he quit drinking beer when he was drinking with my father and hes still been drinking he lied to me saying I could eat with my dad made me eat with his family I cried I was only 13 and my step sister called me a cry baby and she has always hated me because I live with her father and she cant shes outta state and he made my dad wait 5 hours for me at the family restarunt we owned and now my dad only has 6 months to live and ill be stuck with my step dad so what do I do? I know its confusing and has a lot of stories but please help!!!