It sounds like you are taking charge of things. Continue to be the leader. Lead don't follow. It sounds so simple but I'm sure it's true. I know it is in my sitch.
Who knows what your W want to talk about on Sat. Try not to mind read. Go with an open mind and no expectations. No expectations = no disappointment.
Tell you son happy b'day for me. He's three and doesn't care what you do for his b'day as long as you make it his day. It will be special because he's with you.
It sucks so much with little ones. All we can do is make it as good as we can.