Well done OP for telling him to move out and also in contacting the OW and her DH.
Next step is to contact a solicitor.
I'm not suggesting you need to make any decision about divorce at this time but it's empowering to get your ducks in a row and understand what you'd be entitled to, what the process is etc before making any choices.
You need to get in the mindset that you are in control now.
What your DH and OW "want" is utterly immaterial.
After seeing a solicitor also try having a think (or even making a list) of what would need to happen for you to stay in the marriage.
Counselling/job change/no contact with OW etc etc
Then think about if you feel you could really put this behind you because that's what you'd ultimately have to do.
Put bluntly I'm not sure I could get past this.
You found out because he'd been dumped and was devastated. He loves her. He had no intention of ending the affair.
I couldn't live with the idea of being some sort of consolation prize which is what he's treating you as - especially when he's demonstrating how little regard he has by wanting to remain friends with his fuck buddy.