Holiday time can be stressful, plus you are recovering at the moment. Honestly, go only if you feel up to going. If not stay home and rest, I'm sure your extended family will understand.
Some families don't "understand" the above statement. They take great offense when you don't show up for family gatherings and it doesn't matter whether you're half dead or not. The only time it's okay is when it's one of their own.
I know, I was part of one of these families for 17 years.