Boyfriend [36m] cheated and I [34f] am pregnant.

We've been dating since November and ended up with an unplanned pregnancy and I found out he has been text and cheating with multiple women last month. He's taking responsibility and just tells me it was a stupid mistake and promises it won't happen again and he is making an effort by cutting those women off and told me I can look in his phone or track him with gps. The thing is, I was looking through his phone and he still has old pictures of girls and his ex and old texts and girls still in his contacts under different names in order to hide them. Does this mean that he is not serious about changing or is that stuff just something that hasn't crossed his mind? I also found 4 recent photos, but there could be a rational reason for 3 of them. I dont see a rational reason for the 4th one, though. I know I should leave, but if I did, I would be moving 4 hours away and I am 5 months pregnant with his kid and would feel bad about keeping his kid from him.

Edit: We have known each other since middle school, and have been in each other's lives for the past year, but we're disconnected for 17 years before that.

TL;DR: Is he serious about changing?