Bf cheated on me while pregnant

I’m 37 weeks pregnant. My bf just confessed he cheated on me while pregnant. I didn’t find out because he told me but his ex gf reached out and also his sister about 5 days ago. I’ve been crying none stop since and yesterday we finally spoke and he told me everything and also apologized. He told me he would never do it again. Our relationship has been VERY rocky but that is NO excuse to cheat. He knows this and tell me so. I’ve always believed someone can cheat and actually be sorry, that’s why I always told myself if I were to be in this situation I would forgive but never allow it a second time. I’m trying to do this with him. I told him I forgave him and he swears to make me happy and be better. But I’m still feeling down and sad. How could you ever cheat on a pregnant women ?!?! I want to forgive and be able to move on. I’m not writing this post for any of you girls to tell me I’m stupid and he’ll do it again. Because I have hope in him. I need advise in ways I can move on or any advise that would help me out with his situation or if any of you ladies have thru this and forgave your significant other.