I am going through a so called friendly divorce now. We had no major conflicts, didn't argue. Just didn't communicate at all. It has totally devastated my step daughter because she didn't see it coming.
however, I am not going to be friends with my future X. If she doesn't want to be married to me, then I see no need to be a part of her life at all. Holidays or not.
Have you checked your pulse lately? Sure you're still alive? Or human? *LOL*
So your step daughter's mother is SELFISH.....I encourage you to stay a "friend" of your step daughter.....only if to help her be able to learn what MARRIAGE REALLY IS....COMMITTMENT!
Remain friends with your step child, but don't bother with your ex other than to be "cordial". If you had communication problems before, they won't improve with distance. I tried for years to save my marriage, encourage counseling, bring in religious support to no avail. Keep your dignity, keep it clean and if you can let that child know you'll always be there.