Okay she's technologically challenged (which I certainly am so I get it). She knows this about herself. Putting aside for the moment the question of whether she should've shared that letter with you in the first place, she knows what her abilities are. Rather then friend you she should have asked someone for help in copying and pasting to a blank email, to be completed and sent when she had privacy.

As far as writing the letter, in books therapists use generic examples from their practice. As long as she kept it about her feelings and didn't give potentially identifying info about the former client I don't see a problem.

As far as letting you see the letter, it wouldn't work for me because I would see it as encouraging me to take responsibility for her feelings as a way of manipulating me and I had quite enough of that growing up. My task for myself is to not get hooked into that. But what doesn't work for one person may well work for someone else. Only you can know that.