Anonymous wrote:He's an adult. His choice. You don't need to handle anything.
Agree, but he's also a big enough boy that he can then deal with the consequence of having you tell him you were disappointed. I wouldn't talk about it more than once but we don't do things in a bubble, if something we choose to do hurts someone we love (his mother) then it doesn't mean you are free from ever having to hear about or acknowledge that fact/hurt. You shouldn't bring this up over and over or hold it over him- you need to make peace with it and him- but its OK if he knows that you were hurt by it.
I found out that my own dad did something like this- his dying grandmother wanted to see him and he wouldn't go and went only to the calling hours briefly because he "couldn't handle it" and "didn't want to see her like that".