Need advice..

Okay what if you and your baby daddy live together and you're 6 months pregnant for him. And you went out of state to visit your family then you can back and find out that he been chatting on you and he bring and girl and y'all bedroom and they been have unprotected sex a lot.. The girl he chatting with you call his phone then you answer and she told you everything that been going on between them to.. Like what will you do