Hi,
sorry if my post was a little nasty, its just that I'm sensitive to people who cheat. I wish people would get divorced first and then find someone new. Since he's marrying her, I think you should put aside her bad feelings for you and for your dad's sake. It isn't good for you to be seething mad in relation to her. What's done is done and you have to make the best of it. If anyone makes a fuss over him marrying her, then he'll just push those people out of his life and still go ahead with the marriage.
I agree your birthday should have been you and your dad, but once he's married then you will have to get used to her being around. Just be polite and civil - that will keep things peaceful.
If your dad does have a nasty side, then I don't have alot of hope for this current relationship. I think it will fizzle out in the future. Also there's the saying "once a cheater, always a cheater" - I wonder which one will cheat first - anyone in the mood to BET LOL.
I hope everything works out between you and your dad. TC