I'm going to work on a movie set the night of my son's surgery
Why would you want to work instead?
Because I can't treat my kids well, so sadly they won't take care of me in my old days.
Your son may not make it which is really stressful, so I can see why you want to run away. But you need the courage and face your son and be for him when he needs you the most. He will resent you for putting work over his life, even if he understands your reasons.
I'm a man and I have to work. It's inevitable I won't be there for some time. I'm doing my best to be on time for his surgery.
I think that as long as you are closeby, it should be okay. I get that you have to work, but you should make sure that you can be there just in case anything where to go wrong.