Can guys change when they cheat?

My boyfriend and I were together for 3 and a half months before I caught him out talking to his ex girlfriend he dated for 2 and a half years. They were speaking through Snapchat messages for the entire time he was dating me, he would pick her up and drive around with her and talk dirty and send each other photos.. unsure if they slept together because none of them will confess to that part. But I still consider what he did to be emotional cheating, I felt stupid I didn’t notice he was doing this behind my back sooner..

I am having his baby I am 12 weeks and 2 days. So I am trying to make the relationship work because of that, so my question is..

Can men who cheat physically or emotionally, can they change?

He says he wants to change and he now calls me every morning and night and blocked all contact with her.. but all it takes is time to tell, I just wanna hear anyone else’s experiences of dating a cheater.