Lama Ole’s answer:
The best is to think that everybody benefits the most this way. You can think, “If they disturb me then they will also get bad karma, and I can only help them after I have gotten some distance.” You only need to justify it to yourself. To them you say something that can emotionally pass as a reason, and then you happily walk away. And the flimsier the explanation is, the more they will be forced to examine their own situation.
If you come in with a big, extensive explanation, with points and sub-points, and whys and wherefores, then they can address it on a conceptual level. Instead of this, the best thing is to say something like, “I often got headaches when we were together”—something completely subtle and feminine. Then they’ll start to ask “Why?” But by then you are nowhere to be found.
A gnawing feeling will remain with them. They’ll ask themselves, “What was that? Why headaches? Why would someone get headaches from us?” So you leave something that will keep on scratching and digging for a long time. Then you have left them a good gift. You have set something in motion with them.