Hi SOA - Welcome. Glad you came here. Thank you for posting your story. A lot of members will appreciate your perspective.
Unfortunately, when you play with fire you eventually get burned.
He had ever right to react and be upset. I can definitely relate to the feelings of betrayal, mistrust, etc. BUT if you love someone enough you will DO ANYTHING to WORK it out. That's the part that is not adding up.
Have you guys been unhappy for awhile? Why was he so quick to walk?? From my perspective it looks like he has been checking out for awhile. Or he might have been cheating on you as well. Unless you are dead emotionally these feelings cant be turned off overnight. Once again. He was hurt, felt betrayed, blah but if your partner is remorseful and is willing to do THE WORK to REPAIR then it's a whole different ball game then what the rest of us members dealt with.
My advice is to stop PURSUING, stand your ground, tell him you have ALREADY APOLOGIZED for what you did BUT it takes 2 to get to the point where you're at. Show strength. Show respect. Dont kiss his a$$. You made a mistake BUT have owned up to it which is more then a lot of people are willing to do.