Please help

So my boyfriend and I have been dating for almost two years come September.we have the same birthday. I'm 21 and he is 31. I'm in love with him and do all I can to keep him on the right path. I just told my family we were dating in June and I found out yesterday that he has been on a parent dating website talking to women. what would y'all do? I want to have a couple days away or idk what to say. I do all I can and I put myself through a lot with him. our sex life is gone down hill. he never wants to come home when I do. most of the time he won't answer my calls if it's late. if he knows I'm mad at him he wants to know what I'm doing who I'm with and where I am and when I'm going home but when he is mad at me he ignores me for the whole night. idk what to do. I need help