Ah, he is married. Well, there may be a bit of hope then. If he had been fully available, she would have been gone by now...but because he is married and has to handle his outside "activities" in stealth, they simply cannot just go running off into the sunset together. So what to do now?
Well the trouble comes into play in that her grieving will be in concert with two issues...her mother and the OM. You wont know which one she is crying for at any given time. I think as long as the two of you still share the same marital bed (which allows for close proximity if she wants to initiate any touch), and you allow her some time appropriate for her "loss" and do not find that she is going out and meeting up with him (instead of visiting her mother)...then your patience might help.
Just go about your business as usual...be kind to her, but do not make the initiative for touch unless she is breaking down and it seems appropriate. If she pulls away, so be it. If the day comes that she initiates touch on some level, then do not think that it means a green light for sex (sorry)...she may just be experimenting with her feelings to see if it seems "natural" to her. Let her call that shot if and when she is ready.
Do not talk about the affair any more unless SHE brings it up. That wont help. If you need to talk, you can confide in a friend or do it here. Stay off the computer as much as possible around her...she obviously saw that as YOUR "affair" and that is when she felt cold and left out of what she needed to get out of the marriage.
Menopause huh? That in itself can throw a woman into an emotional tailspin too. I went through it in a breeze...but was told that I am the exception rather than the rule. You can compliment her when she wears something extra nice, puts on a nice perfume, cooks a great dinner, or otherwise does something which is pleasing to you...keep it simple, not overdoing it. Once in a while, call her and ask her if she wants you to bring home dinner rather than having her cook...or do the cooking yourself (be a klutz in the kitchen so she will feel compelled to jump in and help you)
. Do a load of laundry, or clean the bathroom without announcing anything. Dont just sit there every evening staring at her. If she asks why, tell her that you understand that she may be "feeling under the weather"...that's all. These little things will help...and little is a start.
The biggest problem I see here is that you will still want to keep tabs on where she is going and who she is contacting. THAT is a really big problem because she will resent it even though she earned it (in spades). My advice is not to do it. If she does not warm up to you, that is enough for you to guage where her heart is, and/or what she is likely doing. I would give it a couple of months simply because of the emotional mess she is in regarding her mother, menopause, and of course, "breaking it off" with the OM. Do you ever go with her to visit her mother? If not, WHY? That relationship is coming to an end too (by death) and not showing a fair amount of support will hurt her deeply if she really cares about her mother.
How did you find out about her affair?