She wrote an e-mail yesterday which I chose to ignore and will do so.

I never did this, but I think I'd advise others to do so: create a mail filter rule which will automatically delete messages from such people.

This way you will never be tempted to read it (thus get yourself involved into this tricky game again).

The only drawback is that one day you can miss a message like "I am dying, I apologize for everything I did wrong, for causing all that trouble, please forgive me" :-)

I would not automatically delete such messagess myself because I like reading what people say, and I know that I can logically isolate myself from getting emotionally touched by a message. It's like the sandbox concept in software - if you have a new program which you don't know if you can trust (maybe it is a virus, or another harmful application); instead of running it on your real computer, you create a virtual one, which is isolated from the real thing. Even if something goes totally wrong, only the sandbox suffers - you can delete it afterwards without affecting the real machine.

If you can create such logical sandboxes inside your mind - no problem; you can read every single message, pay attention to the insults and lies - just for the sake of studying the strategy of the enemy. Once you're done you will remove all these elements from your thoughts.

Otherwise I suggest deleting the email right away, to prevent the 'virus' from reaching out stuff outside the sandbox; so your happy green world stays that way.