I think what you're doing with people who ask you is absolutely spot on! I would say the same smile Not too much detail, just simply I dunno and ask her will do just fine!
I dunno what to say about her anniversary coming up. My H didn't want to know and wouldn't commit to anything. He moved out a week before our anniversary. As for her birthday, I would carry on making plans with her mum, especially if her mum doesn't know what's going on.
If she doesn't want to go to MC, you can put a rocket up her bottom and she still won't go! My H was exactly the same, he said he didn't like talking to strangers about his problems.
Hopefully some of the vets on here will have some better advice than I can give you smile

H47 me48
T22 M21
S20 - Got high functioning autism
3/2000 H admits to OW and moves out to live with her
11/2000 H moves back home
2/4/13 H moves out
H tells me he wants D 6/13, but now he can't afford to!