What should I do with this crazy guy on facebook?

[Keyleo Dashsnow]

Since he asked you a couple of details about your personal life, it would seem that he is trying to get (in this case, maybe he already got it) some info that might help in hacking a person facebook or any online account. Remember, some services in the internet require you to provide some security details (i.e security questions, maiden name of mother, etc.) that would help in case you forgot your username or password. If the guy who you're talking about those acquire these kinds of info, then this might be one reason as to why he was able to hack you.

Another reason might be because he was able just a great hacker

I suggest you change your password and security questions.