At what point is it no longer worth it to confront your parents?

My father was in town recently for our annual mini family reunion. During his stay I saw him at no fewer than three family functions. At one of these functions the old man spoke two sentences to me, and said nothing to my children. At the third his entire communication to me and my children consisted of his ordering my kids to the basement and (literally) yelling at me because I allowed my almost 15 year-old to stay upstairs and visit with some of the adults. Other than this my father did not speak to me or make eye contact and by all accounts avoided me.

I came to terms with my father’s abuse and neglect a long time ago and at this point I feel mostly apathy toward him. The thing is though, his treatment of my kids bummed me out. Plus one brother and both sisters have been trying to get me fired up about his behavior.

The only thoughts I have on a discussing this with him involve sending an email and asking if I did something to upset him. At this point though I am just not sure it is even worth it.

Thoughts?