I'm really not experienced in this type of situation. That said I have experienced infidelity and my husband knew I would KICK his arse to the curb if he ever contacted Ow1 or 2.
Ow1 and 2 both have tried to be 'friends', been pyschos etc.
But you know what, he hasn't bitten at all. I wish he hated them, but he's indifferent (apparently that's ideal anyway). You will hit a point when enough is enough.
Nature girl (a awesome member of this forum) when my wh and I were experiencing DV, answered my question to 'when is it enough' painted it visually for me. That was the breaking point for me. I know I won't accept it anymore and he knows it and for 6 months nothing.
So I want to do it for you
Imagine he's sitting next to her at the table and he's got his hand on her leg, slowly moving up...
How do you know that doesn't happen
How do you know that one day you will arrive home earlier and he's fucking her in your bed?
Okay I'm not as good as it as Nature Girl, but the point is you only know your breaking point. Either way he's disrespecting you disastrously and you are worth more than what you are saying your worth to him.
And he sounds like a fuckhead btw. I mean mine has said things like "moving forward" "our future looks bright" to try and shut me up. But if he ever said that...
He would have a deathwish.