Perverted stepdad

I will try my best to not make this long. I'm a 17 year old girl & majority of my life I have been a victim to sexual abuse. When I was in my toddler years my mom would leave me at my grandma house were my older cousins also lives. I was introduced to so many things at a young age. My older cousin gave me my first tongue kiss😒, he never penetrated me but he still did things to me that a 5 years old should of never known about. Not only him but sometimes even his other brother would try things. They would touch on me, kiss me, ask me questions I never even knew about. When I got old enough to understand that what they were doing was wrong I told my mom. She told me "I don't believe anything you say. You probably willingly let him." I cried & cried. Due to her not getting me any help I became curious on what sex felt like. In 6th grade I started hanging out with older kids which eventually led me to lose my virginity at 12 years old. Sex became a pain reliever for me. Throughout this time my mom had/has a boyfriend who's been around me since I was 3 years old. I never liked him, something always seemed weird about him. One day I gave him a chance and put the dislike to the side. I became comfortable with him, to the point where me and my younger sister felt like we could sleep besides him in the bed he shares with my mom. One day I layed next to him and my sister slept besides me, I began falling to sleep but as I did I felt him caressing my breast and touching my behind. I was so shocked I couldn't move. He did it gently as he thought I was sleeping. I eventually got up and tried to figure out what had just happened. I tried to deny the fact of what he had done. (I was around 13 or 14 years old). As time went by he began to act very weird. He was much nicer, as if he was feeling guilty for what he had did. I debated if I should tell my mother about it because in the past she never believed me. My emotions got the best of me and I ran away from home, the next day the police found me. When I told my mom why I did it of course she did not believe me once again. She told me "if he did do it just leave it up to God, let him deal with it." She called me a compulsive liar, told everybody in the family I was lying, beat me, & blamed it on his illness sickle cells. She put me on punishment for a long time I couldn't even see daylight. Which indicates she didn't believe me. So, I put it behind me, forgave him, & moved on. Fast forward to today. I have a boyfriend who I've been dating for a year and some weeks. He's a really great guy, he loves me for me, respectful, goes to church, spoils me, etc. Everybody and my household loves him except for my stepdad. My boyfriend always gets bad vibes from him. At first it was like maybe he was protecting me because he didn't know him well but now it's to the point to were we feel like he wants to be in my boyfriends place. In the beginning of this year I went through his Google history out of curiosity & found links like "stepdaughter caught masturbating" "stepdaughter & stepdad fuck" & what set me off was the keyword stepdaughter which indicates he still fantasizes about me. He doesn't have a job, he collects disability while my mom works every single day so he has a lot of time on his hands. I was recently put on birth control and I gained a lot of weight. One night my mom and her boyfriend approached me about the weight gain in my stomach, Giving me advice on how to tone it up. My stepdad in particular brought up the size of my ass. I have always been a curvy girl even a few years back. He stated "yeah you can't do nothing about the size of your ass but you can fix your stomach." Which was very inappropriate to me, he said this right in front of my mom! Just yesterday my boyfriend caught him looking at my behind!🙄 I'm so disgusted with him uhhh it's so frustrating please help me