Wow, that is a big test. Having his Mom in the house 2 weeks is just odd. Hopefully she will be your advocate but you got to be guarded about what you say around her. It's not like you can sit around and read books on DBing in front of everyone but you can hide-out on the computer from time-to-time.
I'd let the Mom bring up the R talk and just focus on "acting as if" you've moved-on but I know that will be tough. I would not be concerned about the H's uncomfortable level with your friends and family, that's on him and maybe that will give him some clarity about things.
Focus on yourself and have confidence in all the progress you've made leading up to now, you'll do great!
Me: 42 WAW: 37 Kids: 0 Separated: 06APR13 M:7 Years, T:10 years WAW states she wants to "move on": 01JUL13 "Courage is the standing army of the soul which keeps it from conquest, pillage, & slavery."