They'll usually know I don't think things are going right because I'll have told them when I think things are going wrong, so it usually comes as no surprise. I'd never tell anyone by phone or in a letter, it has to be face to face. I don't have a standard technique I'd have to base how I told them on what I know of the person.

However, I don't agree with all of what you said, while I certainly agree that bad breaks ups damage self esteem and can lead to depression I don't think there's much link with stalking, a lot of times the stalker wasn't having anything that would qualify as a relationship except in their own mind, they can base their stalking on something as trivial as a few text messages.