Feeling guilty

I mentioned in an earlier post that my Mother in law and I went head to head over Christmas and it didn't end pretty. That was before Thanksgiving and we are still not really talking too much. I use to bring the girls over there at least once a week or sometime over the weekend, if not that, I would call her just to chat. Needless to say, this has made our few encounters very uncomfortable for everyone. My Father in law tried to pretend all was "OK" and she tried to talk to me, but, feel the very cold shoulder I gave her.
Today they came over to give the girls gifts and have lunch, it was actually very nice and pleasant. They were here sometime and we even got to a point of idol chit chat. When they were leaving, I could see it in their faces how sad they were that we wouldn't be spending the Holidays with them.
I'm feeling guilty for obvious reasons, but, still feeling very strong about my initial feelings. I believe the Holidays in there family revolve solely around his one brothers family and there is no room for anyone else. This year proving my point almost to easily, as they are having Christmas Eve and Christmas Day to accommodate that sister in law, so she can see her family.
I'm not sure what to do, as I don't want my Mother in law to hurt so much, but, I too don't want hurt feelings.
I must say, I don't feel guilty enough to cancel my plans on going away. In fact, I am counting down the minutes!!!