My complicated relationship

Me and my boyfriend have been on and off since we first started dating in August. He texts other girls but never sees them, I would rather him just block them but he says they are depressed girls who just want someone to love. I know for a fact that he only sees me and not the girls he texts on his phone.  I know some of the girls he texts is in Michigan and he's going to visit his mother there this summer... I wanna trust him but how can I when we have had issues in the past with my best friend who he tried to get me to share him with. I just don't know whether to ignore it and trust him or confront him and probably have to break up again.