He Cheated

So yesterday morning my boyfriend of 2 years got up as usual & took a shower before work. He gets dressed and ready, then he comes to bed and tells me & our 2 month old baby boy goodbye. He asked me what's wrong(nothing was wrong) and I told him nothing & he said I looked sad..I wasn't sad. Anyways as soon as he gets to work he calls me. Talk for just a sec not long at all and says he's got to go. Then I get a text message. Telling me that he's cheated on me 3 times since we've been together with 3 different girls..all of this took place over a year ago & he just now told me. I wasn't sad that morning before he left, it was just his guilt. We moved in together when we were dating for 5 months. 1 girl was before we moved in. The next was like 4 months of living there. Then the next was 3 or 4 months before moving into our new place(and before I can pregnant). How would you have handled this? He said he waited so long to tell me because he didn't want to lose me because I'm the best thing that's ever happened to him. Also becoming a daddy has changed him.