My mom hates because I share my feelings?

I fwwl really uncomfortable when my moms bf stays ovr. I've told her this every time he does. Instead of decreasing his visits she increases it. Thats the other half of the problem. When I say that I'm uncomfortable, she says there's no reason to feel that way and she's in her 40s so its okay. I'm 15 btw. Idk what to do she really hates me now but I can't help my feelings and it really hurts that she completely disregards them. Advise?