It would be a mistake to not give this to him. Not many people receive anything close to a letter that means this much. You know what the outcome could be. I hope by the time he's done reading it he's holding your hand.
OK well if you don't give it to him. you should definitly save it. so when it does happen, you can give it to him when it does happen and then he can feel like a boob for not dating you sooner
Good Luck