Do you think it necessary for me to send her a message? She hurt herself, or to put it bluntly, cheated herself. . .

There is no need, even say, not to send.

You are so persistent in sending this message because you still have some fantasies! But these are still just illusions. ...

If you let go, don't do anything that will remind you of the past and make you sad.

If you do this, she may or may not come back. If you don't come back, you will hate it even more. Don't tell me you've forgotten and won't hate it anymore. That's all bullshit If you reply to the message, what do you want to talk about?

It's not easy to forget someone, but then again, everything will calm down with the passage of time. Put your energy elsewhere, and one day when you remember it, you will find that you have really forgotten her. Good luck!