Hello shameshame, just to say that I got myself into a stupid and shameful situation like this years ago, similar age to you, work thing. Won't go into details, it was a very bad time in my life - I daresay it often is when people do something so hurtful and unpleasant to themselves and others.
At the time, nothing had ever felt so emotionally intense. It did for a while afterwards - I cried every day for a year during it and after I'd ended it, from guilt and from feeling so intense and I am just not like that normally.
But when I look back, little now feels so unreal and insubstantial and has for years. I feel less of substance about it than other real past relationships, it is more like a bizarre dream.
What feels real is how guilty I feel about his wife, particularly when I had my own children and felt for myself how vulnerable that makes you. Looking back, I don't think he was a bad person but I think he was weak and hadn't grown up. I hadn't either, at that point, it got me at a dreadful point.
There is something deeply unreal about these dynamics, please remember that. So trust your judgement, not your intense feelings I'd say. A happy relationship will not make you feel this awful - it doesn't work like that.
Go and do something wholesome - seriously, I took up an outdoor sport of all random things - that has nothing to do with men, because you need to rediscover the fact that you are you quite outside of any relationship and that you'd be a damn sight happier single. Then just leave it.
I found counselling brilliant.