We're all listening Lex,
Put some detail in your story so anyone may be able to assist or at least provide support. Write anything you want, it's your life.
Can you not go to the Police about the ex stalking you. I know you can under British law so why don't you do that.
And you can prevent him yourself doing it by computer. You just change details and keep your real data hidden and replaced by false data. If you do Facebook, just inactivate your record and open a new account with fake data. Most people do. Only suckers stick with real data Lex.
Change email address, Twitter account name, any record that has your real data on it and he won't find you. Phone numbers etc, all of it.
As to physical stalking, confrontation usually solves that. Return the favour with your boyfriend and perhaps a couple of his mates. Warn him off physically and frighten him. Don't make mild pleas. Tell him he must stop or all of you will begin following him everywhere he goes. You see the threat there to him? Nothing illegal. Just power of numbers.
He'll stop, and quick when he realises he's no longer dealing with a victim but has become such himself.
Describe your symptoms for us.
I wished I had been a drummer in a rock 'n roll group. It looks so much fun. But it can be hard work if you are serious as a group.
Drop a written note in his letterbox at his home telling him you and your friends have turned the tables and are now stalking him, all day, every day. It doesn't have to be true just yet but it can be, right?