Confused

My daughters father cheated on me while I was pregnant and slowly I have been trying to get past it but a friend of mine told me he plans to propose next week. I would think I would be happy but I’m not . I don’t know what it is , but I think I don’t forgive him . Loyalty is very important to me and I still feel betrayed by him. He has become a better man to me since then but I’m not sure if it’s because I hold grudges against people who claim they love me and do things to me.i don’t know how to feel, I just know I don’t want to marry a man who slept with another woman , domt care if it was just one time and I don’t care that he has changed completely.