Sorry, I dont think going to Police will achieve any
results.
I dont think he breaks any law by refusing to delete a file in his
HP, which he took with the parties' consent.
I really dont think going to Police will help at all.
Rather, you should just try to keep a friendly relations with him.
Dont antagonize him, dont make him want to sabo you.
Sorry but I think that is the only way really.
There is another method of course, if you dont like to live with a
sleeping time bomb and leave it up to your ex-BF kindness.
This method involves abit trick.
You should find a way to get a hold of his HP, and delete the
file.
How you achieve this is up to you.
You should think carefully and devise a plan, and also find out
whether he back up his files anywhere or not, because you need to
delete all of them.
Ok good luck ok.