Father of my unborn child lives with a woman

I met my boyfriend,now to be father of my unborn child,at a party that me and my ex was suppose to.attend,my ex didnt show up and so I met him,when I met him I was living with my ex which is also the father.of my son,he was living with his girlfriend,my ex was so abusive and.my boyfriend told me to leave him he love and want to be with me,I did 3 years in the relationship I posted that we in a relationship on social media thats when his.girlfriend found out about me,he is not not with who he lives with,we have sex in the house when she goes to work we even have sex in the basement while she upstairs sleeping,he sleeps in his couch at nights so she wont know if he inside or not,they not sexually active as he said he.didnt love her and never was he attracted to her,I left my clothes by the hosue I do whatever I want,he not leaving,dhe come to my block to.see his car and.start calling his.phone,she track his call to see.how.often we.speak,he cries daily telling me please not to.leave him am the woman that make him happy,am now pregnant do u think I should let her.know or let she.find out on her own ,she doesnt have any.kid for him,he is a very good man,buys me call ,bring me places ,helps.with my bills,now.sending me thru college,I dont think she is a baf woman ,I think she more carr about his.money than to make.him happy,what do u think?