Sex with an ex?crazy?

Just broke up my first boyfriend and he's the guy that ive been totally inlove with but sadly we broke up.We've known each other for mere 7 mos. until now Im currently not involved with someone.If i do ask him to have sex with me no strings attached will it be an insane thing to do?He'll probably laugh at me if i do this.Is there any way i can let him to that wont freak him or just stop this urge?