Who supports what you want? Do you have people there with you who agree with some of the stands you're taking?
It's really difficult to navigate with in-laws! Even though it doesn't work with my sitch very well right now, I still think it's a good idea to "not talk" about WH stuff with them at all.
"Being vindictive" over the name-- it doesn't have to be! It can just be a calm, thought-out decision. (I'm rolling my eyes at MIL.)
Collecting his stuff-- are there any things you guys might argue about? I'd get ready now and put them on a mediation list to go over with a 3rd party.
I totally understand being over WH. I'm kind of getting there, too.
My only thing is-- a civilized separation is better than a contentious one! Just stay strictly logical and interested in peaceful separation.
Good luck, P. This separation crap will be over soon. I'm glad that mine is in the past!