Wow, sounds like she has a huge problem, and is hypocritical too I get a kick out of people that after they "clean up their act", they want to convert the world and some think those that do not follow their new found ways are bad, grrrrrrrrrrrrrrrrrrr!
She should pay more attention to her daughter's wanting to cut", it isn't because of your son and her relationship, it is probably due to the long term relationship with mom and the things maybe mom did in the past way before your son knew her. Le's face it someone like this woman will probably blame everyone else for her possible neglect of this young girl, maybe her mom was too busy in her own selfish ways? Who knows, I do not want tojudge her either, but it is very unfair thee way she is judging you and your family, she has no right to do so. I know of some people that go to church, some daily and some of them are the meanest, most evil hippocrits, perhaps they go so often due to their guilt of their wrong doings. It is ignorant of her to judge people and their religion or lack of it, religion and politics are 2 subjects that only fuel arguments and has started many wars around the world.
If at all possible stay away from this woman, she still has some major issues she needs to resolve within herself.
Now, the hard thing, how do we get her daughter into good counseling to prevent her cutting? Anyone out there, please add to thsi thread with any suggestions, cause it seems if "somebody" was the one to show concern for son's gf then chances are this other woman would cop an attitude and say or do more toxic things.
Somebody, I feel for you and your son, if he can maybe it be best if he broke off with her, it is painful but with the interferrence of her mom could only lead to more heartbreak in the long run.
Just my 2 cents, pretty long too, eh?

Take care, and know you are both "good people" regardless what this woman says or infers.
I am wishing you lots of love and luck, Always feel free to come her and rant, socialize, chat, or whatever, we are all here, dear person

DE

In giving advice seek to help, not please your friend
SOLON