He cheated. We opened the marriage instead of ending it. Six months in — does this ever work?

Im [F37], married nine years, two kids, we live in Mardyke. Last year I found out he had been sleeping with a woman from work for six months. Classic — found the phone open. Wanted to leave that hour. But the kids. The house. The thirteen years we built. After three months of couples therapy we tentatively agreed to open the marriage formally — rather than have him cheat while I seethed. Both free to see others, rules written down on actual paper. Six months in. He still sees that colleague, I know it. Ive seen two men — first was lovely, second made my skin crawl. Stood in the bathroom one morning looking at myself wondering who I even am anymore. Does this actually work or are we just stretching out the inevitable? People whove walked this path — tell me honestly what happened two years in.