Stepfather.

So my mom has been with this guy since I was 3, I'm 14 now and they're still together. Well my stepfather and mom get in alot of fights and my stepfather is still with my mom. He even cheated on her. I got a bf this past year and lately he's been treating me like shit and when I get in shit he threatens to stop us from seeing eachother. He doesn't like us hanging out. I have come to really dislike him. Should I tell my mom how I feel?