Moms bf is trying to bang me...

Am

I live with my boyfriend and his mother she has about 3 kids... but her on and off again boyfriend is trying to fuck me.

He tells me that he watches me when I’m in a towel going to take a shower. He notices how my ass jiggles in certain outfits. And he just wants to know if he can taste me.

I’ve played it off and laughed cause I’m not good with these situations but I’m 9 months pregnant and very uncomfortable. I’m battling with myself to tell my bf mother.

Cause I know once I tell her shit can either go 2 ways. Sigh this the 3rd in counter where I have been put in a place of being un comfortable with a man I considered a friend.

Should I just tell the mom whiles not around ?