Which would be more upsetting to this person, going and not acknowledging them or not going at all?
Probably neither. It sounds as if you are "annoyed" with someone; the someone probably has already "forgotten" you. Often that is what happens. So, go to the function if you want but don't base your going or not going on "someone else".
true that we can only control how we feel about situations. we cannot control how others feel about us. be happy control your happiness it is not in there hands but yours. breath and eat cake you will tell bigger stronger wiser and kind for eating the frog and moving forward and free of toxic thought and bitterness when life gives you lemons make lemonade.. smile it's all good