Help I HATE my mom!!!!!!!!!!!!?

My mom and I were always very close. I was also close with my grandma shes only 55 so no like she old and not fun or anything. My gram is crazy but i love her. I would talk to her on the phone every night before bed because she live far away in FL with her brother, my moms uncle. I would visit my gram 2 times a year. But last summer I went to visit her with my 2 older cousins they are 14 and 15 and im 13. WELL my cousin are sister and they smoke and do pot and stuff but their parents don't know. My uncle who lives with my gram is a big pot head hes and asshole i hate him..he thinks hes a philosopher. While i was there he made us smoke pot and cigarettes and got me drunk. I was sexually abused when i was there. My gram had no idea what was going on because she was always at work. By the time i arrived home my mom noticed i was different and my aunt noticed the same with my cousins. I tried telling my mom but she didn't believe me. eventually my cousins had the same story as me and my mom believed us. she cut off all contact with my grandmother and told me I was no longer to talk to her. I hate my mother for this, there's not a day that goes by without me thinking of my experience. My grandma didn't do anything! It was all my uncle! Anyway since then my mom hs been going on like none of it happened like im fine and perfectly normal BUT im not! I don't know what to do.