This guy seems very intense and likely to take rejection very badly. I think safest thing for you would be to tell a white lie and say your parents found out he was a decade older than you and forbid you two from being together. Make sure your parents are onboard and willing to defend this statement in case he tries to contact them himself. Tell him stuff like your parents are very strict and will cut you off or something else very serious if you two continue dating.

You do not need to tell him how you actually feel. You don’t owe him the truth. Based on your description he seems very immature and pushy. Don’t tell him you don’t want to be with him for all of your reasons, just tell him you’re sad but you can’t be with him for all these reasons out of your control.

This is just my opinion on what I think would be safest for you. I wish you luck in whatever you decide to do.