Divorce is not admitting defeat. It's often the only sensible decision. Staying in a marriage with someone you can't trust is admitting defeat.
My marriage was three times longer than yours and when my ex-husband resumed contact with the same OW he had promised decades before he would never again be in contact with, I divorced him without a second thought. He had gotten another chance and he blew it. And, yes, there were all those promises that he didn't mean it and it would never happen again and I was the only one he loved. I didn't buy it the second time.
I wish my marriage had worked but it didn't so I fixed the problem.
No matter how much I want it to work out I can't accept the lack of trust or the betrayal. I can't think of a way to make it better. He can't say or do anything to change that. I mostly believe what he is saying but there is always room for lies. If I stay it would be more like a business arrangement for our kid because I could never actually expect fidelity. Not sure that is anyway to live.
We just moved into a more expensive house last year and it was a hard adjustment for him my child who is 5. If I was certain I could keep the house then I would feel better about it. I think I can but it would be tight. It is a great neighborhood with a good support system I have been building. Is that rationalizing?
Never mind my codependance craving to save my H from himself.