Hey NW: I don't know if you'll get this before the party - but I just wanted to say hi and wish you the best. You're attitude is just so strong - and I think you've managed to detach in a way that very few people ever achieve - and that should make for a very healthy you - and a very healthy role model for your son.
I've been getting some of those feelings of resentment/anger too - but I just don't listen to them for very long - as I think they come from desires and expectations - rather than a real commitment to myself and my kids...still, I understand the feelings completely.
Just today, as I landed in Cleveland, I could not help but think of what past Christmases were like - I recalled being here three years ago - just after my H's affair - and how terrible it felt to get off the plane and then get to my mother's house - only to watch my W run up the stairs to call her "friend." And then I thought of last year, being here with our baby - how much fun we had - how much we played - and I thought of how I had done something I had never thought myself capable of doing in forgiving her her affair...and yet she now has the gall to tell me that I'm incapable of loving someone...
And then the resentment fades as I remember that so much of what she says and does has to do with her - not me - and taking it personally is just my ignorance allowing me to play into her idea of how things should be between us and for me.
I'm glad the anger goes away as quickly as it comes up for you - that's probably how it should be - just let the through rise, acknowledge it, and let it go...very Zen.