Ellie (kml) gave you some excellent advice. Live well, cherish and celebrate life! You deserve it.
I had to deal with simliar issues with my D and rarely see or speak to my ex's family anymore. I was there with him for 16 years and even helped take care of his mom through hospice and was there the morning when she passed. I keep up with them a little here and there through Facebook, but that's about it. It hurt at first, but I am used to it now.
You will always be connected because of the children, but you're going to be okay if you are not as close to them. If you can find a way to be around his family and not hurt, then enjoy the time with them. It's a fine balance and certainly understandble if you put some distance there. Just remember that you'll always be connected, and if they want to remain close, I hope you can find a way to do that.
I know the holidays are still hard on me, with my kids bouncing back and forth like ping pong balls, but I do my best to keep busy and each year it gets a little easier for me.
Happy New Year!
Me 47 Ex H 46 Bomb 9/02 D final 3/04 Ex H now married to OW
------------ This is surviving. There is no such thing as a normal life, there's just life. So get on with it and enjoy it!