I did pretty well actually. Really well come to think of it.
I got home a little early, put the presents the kids picked out with me in a birthday gift bag, and let the kids give them to her. She acted excited.
Afterwards, she told me thanks for her gifts. I replied that the kids picked out the gifts, and that I just paid for them.
Since the kids wanted to take her for dinner, we then went to a restaurant W chose. Nice dinner. I can only describe it as pleasant but not fun. Was fine, but I would not want to do it again.
We got home and W baked her birthday cake. I offerred to buy one Tuesday evening, but she said she would just make it. Was better than anything I could have bought. She really is a good baker (and cook for that matter).
I did not strike up a round of "Happy Birthday." I did not give her a card, present or anything else. And, not out of any resentment or anger - just letting her new reality set in for her. True reality would have been me not being there - but the kids don't know about our problems yet, and me not being there would have been the first time that's ever happened.
I stayed calm and assertive the entire evening. Throughout the evening, W initiated conversation with me. I responded politely, but with short answers. Not curt, just shorter than someone who wants to have a conversation.
We both retreated to our separate bedrooms early. I watched a little TV in my room, then went to sleep.
I felt sadness for W that her birthday had to be this way. But, I know I did the right thing.