Just stopping by to check on you. Sounds like are going relatively well. Your H admits the M is saveable and is maybe in MLC.
I agree with Ellie about the in-laws - suck it up and be polite if it kills you. It is best to avoid introducing any new issues or stirring up any old ones.
I don't know why your H asked the question about affairs - maybe you should be open about the fact that you are going to meet with non-threatening or female friends. Sometimes if the WAS is insecure - the whole secrecy about your life thing can backfire. No need to explain your plans in detail - but just enough to he knows you are not seeing anyone else.
I think you are handling his work issue well. That is what my male coworkers really need to talk about - sometimes they go on and on and I fall asleep! LOL! Men don't really talk to other men - and despite all stereotypes, they do need to talk - so listening to his work stuff may just be part of his love language.
Also I agree with you not making an issue of having to adjust his routine schedule with the kids b/c of work - that was a big conflict for him with respect to his decision to separate. Show him how he can spend even more time and have more flexibility with his kids with you in his life.