I agree, it sounds like she's noticed that you're not at her beckon call anymore and it pisses her off. I don't know if she's doing anything conscious to "keep you on the hook" but she sure as hell is doing it.
The trick here can be found in threads like Franks and some of the others who got REALLY good at deflecting this anger and resentment when they decided to not play the reindeer games with their wives.
It is important that you don't try to justify yourself but at the same time, I also think it's important for you to remain calm, nice and seemingly eager to talk to her.
The idea is that you DO want to talk to her, and you DO want to be there for her, but just like her, you have a life and there WILL be times when you are not available. If she'd like to be polite, like she would with anyone else, and leave a message, you'll get back to her as soon as possible.
She has to understand that this is not so much a reaction to what she's done/doing but you just getting back to a condition where you're not living life for someone else and this is just a part of that. You do that by, again, making sure that you don't come across as bitter, seeming to say "Well, f--k you honey, if you can have an affair, I don't have to answer the phone...". You just want to present a calm, collected (NOT aloof or condescending) demeanor and really kill her with kindness.
She will likely NOT respond with kindness, but rather more anger and such, until she finally gets that you ARE still there for her, and probably DO still love her but that you are not going to be walked on anymore.
This SHOULD be a good thing in your sitch in the long term but for now, it could get rocky.
I never really did too well with this kind of thing which is why I directed you to Frank. He was really good at maintaining his positive mood and outlook while his wife tried to project her anger onto him.
So, the key is to be unavailable (because you really ARE unavailable) but not be an a$$. Never be an a$$ about it. This is not about revenge, it's about self-discovery, GAL and growth.
