Childhood Trauma Causing Fear of Male Dominance?

As a kid I grew up without my real father (he cheated and hit my mom but I was too young to remember, I only know because of stories I’ve heard). I grew up with a stepdad instead, he could be fun most times, we’d go out to beaches, parks, restaurants, etc. The problem was when we’d get home he was severely verbally abusive, as well as grabbing me by the collar of my shirt when I’d do something “wrong”. I was about 6-8 when I endured the worst of it, I remember getting in trouble if I didn’t like certain foods that he had cooked for me and I’d be forced to eat. Or when I had gotten out of the shower and dried myself with a towel, he just walked in and told me that I had faked a shower since my skin was already dry, and he’d force me back into the shower, call me a liar, dirtbag, etc. And of course I’d cry, and I’d get in trouble for that too. I wasn’t allowed to have my step aunt (his little sister) put makeup on me, he told me to “take that s*** off” and ever since then I make sure my makeup is hardly noticeable. He also didn’t allow me to wear a swimsuit because it was inappropriate, and since then I always cover up my skin and feel ashamed and over sexualized if I don’t. My mom never stood up for me, she called me names and sided with him for the most part but I forgive her because he abused her too and I think she was scared. He took away a lot of my confidence but at 17 I regained a lot of it, I now dress how I want and do my makeup. So now I’m 19, in the most amazing relationship ever, but, whenever my boyfriend initiates sex I feel my stomach sink, I get nervous and tell him I’m uncomfortable even though I really want him to. I’ve done this since we started dating pretty much, and it makes him feel unwanted. Never did I even think that maybe it stems from my childhood and the fact that I’ve never had a healthy male really in my life. And the last time I did, it was abusive and I had no way out? How can I move past this fear if that’s what it is? Or just let me know your thoughts?