He says he’s changed ? Do i believe him?

Just trying to see if I’m being overly emotional or what? So me and my kids father are no longer together but he’s been asking to come back saying he’s changed and what not but i don’t know if i believe it or not. I really don’t want to be hurt again but i also feel like I’m giving up too easily. He has hurt me a lot and i slept with a friend a couple of times to get back at him. But I’m currently 4 months pregnant with his baby(not the friend). He was abusive in the past but we have both be in counseling to get better. It’s just he has said he’ll change in the past only to keep doing things that hurt me. But he wants me to cut off the friend i slept with and i told him no because i have known him 11 years a lot longer than my kids father and i don’t even like my friend in a sex way. I was just hurt and wanted revenge. I don’t plan on sleeping with that friend ever again no matter what because i simply don’t find him attractive. But I’d feel like a fool if i got bac together with him only for him to hurt me again. But i want my family to work. I grow up in a very chaotic environment and i don’t want that for my kids. He’s says he’s changed and i want to believe him so bad but I’m scared of falling back i love and letting my guard down and he hurts me again. Am i just being overly emotional because I’m pregnant? Should i just let it go and coparent? Or try once more to see if he really has changed?