Triangle of love and despair

ok, SO my boyfriend and I have been together for a total of 5 years. Last year I found out he was cheating on me so I left him and tried to move on. We didn’t talk for about 6 months until I finally decided to call him on what would of been our 5 year aniversiry. We decided that we were going to work things out and I was going to forgive him because we loved each other. Then a few weeks later he tells me that when we weren’t talking he had a “NSA” relationship with this girl and it was JUST sex… and now she is pregnant . I love him and want to be with him. But can’t stand the fa ct that he is haviong a child with another chic!!! this chic says she loves him and wants to be with him… One night a week he goes over there and stays the night to keep her happy. and we are constantly on the look out from her friends. he SWEARS that NOTHING happens when he is over there and I believe him. Her pregnancy is high risk and I don’t want to do anything to piss her off … bbut how can I stand my man staying the night at an ex lovers house??? I still have 4 months to go as she 5 months pregnant. plus she foind out my house number and keeps on calling me and harrrasing me telling me that I am taking a childs dad away and if he is with me he can NEVER see his son. I don’t want that to happen!!! But I love him!!!

PLEASE SOME BODY WHAT DO I DO