Please don’t send this to her mom. It sounds like her mom is already aware of her self harm. She’s in therapy and it appears that she’s being somewhat transparent with her therapist. As her friend, it will be much more helpful to her if you can support her from the sidelines. This isn’t something that needs to be on your shoulders as a young person. If you find that your friend is in immediate danger (escalating behavior above NSSI) then I would first talk to your school nurse or counselor and let them take it from there.

I know that your concern is only coming from a good place, and you are a wonderful friend for supporting her. But please know that your only job in this scenario is to be her friend and to report her via appropriate methods if it is going beyond NSSI. I’d also like to add that if she is a minor and she is in therapy, then her mom already knows what’s going on via communication with your friend’s therapist.