I'd say this amounts to 'pursuing a course of action that results in harassment' or similar which is punishable under Protection from Harassment Act 1997.
I'd be reporting it to the police, good chance it'll result in a restraining order and those are no joke these days when it comes to applying for jobs.
I'd be reporting it to the police, good chance it'll result in a restraining order and those are no joke these days when it comes to applying for jobs.

You've done exactly what you need to do to solve the situation. On that note, I don't think there's any more to add.