I cheated on my partner and would like his full forgiveness

I (44F) met my partner (48M) in 2005. I got pregnant very early on. We were never officially together, but he supported the pregnancy and has always provided financially for our daughter.

Over the years, he dated other women and had another child with someone else. I stayed in love with him the entire time. I even asked him to father my second child because I didn’t want multiple fathers for my kids. He agreed, but we still weren’t in a real relationship.

In 2018, after 13 years of this dynamic, we finally decided to officially try as a couple. However, co-parenting with the mother of his other child has always been uncomfortable for me. The mother of his child and his daughter visit annually. Some of these visits happened in my absence where it was just them for long periods. I’ve expressed discomfort, but he sees nothing wrong with it. I’ve often felt like I come second.

I’ve also asked about marriage multiple times. He avoids it or says we need to be more compatible. I later found out he had previously been engaged to the mother of his other child, which hurt.

In 2023, during a period where he was distant and his mother was very ill, I cheated. It was wrong. A month later, his mother passed away. The timing made it even worse. I take full responsibility for what I did.

We are now almost three years past that. I’ve apologized consistently and tried to show change through my actions, but he hasn’t forgiven me, and we feel stuck. We’ve officially been together almost 8 years.

My question is this:

Given the full history, does this relationship sound salvageable?

am I fighting for something that was never truly secure to begin with?

Or is it possible for someone who’s been through what he has been through to forgive?

Or should I just let it go and let him be?