Sorry if I'm out of the loop by why are you going with W anywhere??? Is she not still involved with OM? Has she recommitted to your M?
What are you celebrating? If you cancelled to make a point then why are you still doing something with her the same weekend you had plans? I would think the point would be, Sorry W that doesn't work for me, maybe some other time?
I could be wrong but I think she still knows she has you very much on the hook.