Cheating baby father.

How can i get to the point where i just don’t care what he does?? I have a month old daughter and i just don’t trust him. He cheated on me a few times while i was pregnant & i stayed because i live in his house and really have no family. He promised me and told me he doesn’t want to lose his family and it’s different that his daughters here he’s not gonna cheat i believed it but lately our relationship has been shit.. i hack into his Facebook and he puts on his story to ask for his new Snapchat.. if he didn’t tell me about it i doubt he’s up to no good.. i just want to get to the point where i don’t care. It’s bothering me so much right now and i feel like it takes me away from truly enjoying my newborn because he’s such an ass.