11 weeks pregnant

Ok so I’m 11 weeks pregnant with my boyfriend, I found out he’s been cheating on me, I’m paranoid all the time thinking he’s up to something, I love him so much but I don’t trust him anymore, what do I do? How can I be strong enough to leave him for good and not go back, how do I get the thoughts out of my head picturing him with another women, it’s killing me, what do I do when he keeps coming back to me, I’m not strong enough to leave him