Feeling depressed

I’ve been with my husband for 9 years married 7. We have two kids. He cheated on me 4 years ago without my knowledge, I did not find out till a year after his 6 month affair. I felt we were in a good place after that hear of hiM secretly fixing us when I never even crossed my mind he was cheating. Well here I am 4 years later and I still always think of this situation because if I was aware I wouldn’t have stayed with him. Our son would have never been conceived along with two prior miscarriages. I feel so guilty and broken and selfish. Am I unhappy with myself, am I hurt still over that. I’ve talked to him about it and ask for reassurance which he replies I can not promise I won’t cheat again I don’t know the future. Sooo..... do I leave him... am I unhappy with myself or unhappy in this marriage. I feel so lost and unhappy with my life but love my kids so much and want to give them a better me ... any advice... or hugs