My friends ex won't stop mailing me on Facebook?

[Sophasaurus]

He sent me a friend request and I thought 'oh, I know him' so I accepted it. And since then he keeps messaging me sometimes asking how I'm doing other times just saying 'hey wassup'. He puts 'xxx' on the end most of the time. Although this sounds really mean he isn't very good looking (spotty, glasses, kinda short)
Also while he was with my friend he would get really angry at her for nothing and called her all kinds of horrible names via text. I know she still likes him a little and its getting awkward because he messages me like 3 times a day and its getting a little stalker-ish. They both go to a different school to me. Should I tell her he won't leave me alone or keep quiet?

[Vanessa]

Delete and block him off Facebook and if he continues talking to you then talk to your friend about It..

[A Directioner]

Unfriend him on Facebook and block him. That should keep him away.
But if it goes out of control, like he visits your house, stalks you when going to places, you should report it to the police..