Have been following your sitch on and off, decided to read up on your sitch!
The reminder thing is tricky. Seems like you're doing the wrong thing regardless of what you do. But I have to agree with Mishka, when you "I want to remind you", it insinuates that you have already told him and think that he probably forgot. Do you talk to him on the phone sometimes? If so, in the middle of the convo, you could say something like: "Oh! Hey, BTW, about the graduation tomrrow. Do you want us to meet you there or do you want to drive together?" That way, you come across as assuming that he has remembered and just wanting to finalize the details. If he didn't remember, he has the option to just pretend he did without accepting any blame.
