My stepdad might ruin my relationship?

My stepdad and I fight all the time and have a horrible relationship with each other. He talks down to me, criticizes me, makes me feel bad about myself, and has no respect for any boundaries i try to set with him. My boyfriend used to help me with all my problems and was my confidant but he recently got hired as a helper for my stepdad who is a self employed roofer. I tried to tell them and my mom how uncomfortable i felt about them working together but i didn't make a difference and my boyfriend told me that my stepdad trash talks me when they work together but i feel like sooner or later my boyfriend might believe my stepdad. My stepdad has also been invading the privacy of my relationship with my boyfriend like threatening to beat him up if he hurt me and stuff which also makes me uncomfortable because it feels like he thinks i'm incapeable of taking care of myself with that type of thing. Yesterday i was crying my eyes out because my stepdad was talking down to me and my boyfriend told me i brought it on myself because i'm apparently "rude" when really i didn't do anything wrong to solicite it and we had gotten in a fight the day before because he didn't like how i reacted when i was upset about him and my stepdad working together and i wasn't talking to him for a little while so we wouldn't get in a fight which i guess i couldn't prevent. So while i was crying my stepdad kept pressing me for what was wrong and i told him that i would rather not talk about it and like him to leave it alone and he called my boyfriend up and asked why i was upset which in my mind was a total violation of my privacy and was disrespective because i didn't want to talk about it and i wanted him to leave it alone. My boyfriend and I got in a fight today when i told him how this was all effecting me and we got in a fight because he said that when he finally found a job that i was ruining it when i tried to explain to my stepdad before that I didn't like the idea at all. I feel so powerless and like my feelings and opinion mean nothing and that regardless of how insecure and uncomfortable this is making me nobody wants to see my side or compromise. I don't want to lose my boyfriend and I'm terrified he'll leave me but I have absolutley no idea what to do. I can't take it anymore! Anyone know what I should do? my boyfriend is almost starting to make me feel like my stepdad does.