Boyfriend cheated

I don't know what to do, I'm an emotional mess. I found out the other night that my boyfriend has been sending nudes to other girls and asking multiple other girls for nudes of them. The most recent occurred the same day that we confirmed I was pregnant at the dr office! I'm still in shock that he would even do this, I love him so much and he claims to love me, he was the one who wanted us to get serious and he really wanted to have a baby and now that we are I find out he's been doing this and I'm so hurt! I don't want to leave because I love him with all my heart and I really want to believe he's going to stop but I'm having a really hard time believing that he will and that I can trust him again. Has anyone had this happen and their boyfriend actually changed and become completely faithful?