I have been in a very similar situation and I can tell you that (at least here in California) the police will not do
A N Y T H I N G to deter someone who is harassing you. Many people have a very false security about what the police will/can do.

You can get a restraining order, but unless the guy has a history/criminal conviction of having physically abused you (and unless there is a minor child involved) a restraining order is best left to TV programs. IRL they aren't worth the paper they're written on.

Here's what you MUST do if you are serious about keeping this bum out of your life: Do not respond to any of the guy's attempts to communicate with you. DO NOT RESPOND. At all. That means, block his number. Do not listen to his messages - the second you think he's left a message DELETE (don't 'just listen to it this time'). Filter his email address so it goes directly into your trash bin, then delete all of your trash email without peeking at who sent what. Make everything private on Facebook, if he can find you there.
You get my point...If you are 'tempted' you will be giving him hope that he can see you. Be bluntly honest with yourself, because no one will 'keep the bad man away' from you except YOU.