I think you are doing great! I also think your feelings are normal. I know that it bothered me even last year that H married OW and I wondered which of his relatives went, which ones "accept" it all. They didn't in the beginning - who knows now. Who knows what he has told them. But I've come to accept it and life has been fine. The more I have distance the more peace I have felt. Strangely, he has been coming out of the woodwork this Christmas. Calls the house every day (I NEVER answer), took the kids for a bit more of a visit, calls to check on Ryan (with the nurse) and didn't understand why the kids didn't want to spend his birthday (this Thurs) with him despite the fact they have tried every previous year and he has turned them down for OW.
Regarding the Santa gifts I think that's one thing you don't have much control over. There are some things we just have to let go on and as one of the other posters pointed out - it makes the kids feel extra special. That can't be a bad thing.
Anyway, I'm thinking of you and glad this holiday has been good.