Ok, if she really said that, leave it alone. Write her encouraging letters every now and then if possible. Breaking all contact with someone you've known for a long time is also traumatic.

Both >>6 and >>9 have a clear point: you have to be stronger and confront her. Don't be afraid of losing your relationship. That's the least you will lose if things go well. The worst is that she can commit suicide. (Depression for a long time does that.) Face the facts: right now she's not your girlfriend. She can't think.

However, there is one thing that stops people from suicide and that's having a deep connection with someone. If she really feels needed by you, and she also needs you, at least suicide will not be an outcome. Since I don't know how close you both are, I can't tell if she feels that way. BUT IF YOU break all and any contact, you could be permanently breaking that very bond that existed between you two.

Make her explain everything to you: what makes her upset, what's on her mind, what are her fears, EVERYTHING THAT'S GOING ON. Then, you, with your critical thinking will tell her "I feel you. It's alright. I'll be here and I want to share your pain". DO NOT come with your "critical thinking" as >>9 fucking said, cuz that will ruin it for her. Sex is also a NO-NO. She could be temporarily fine, then get into a WORSE RELAPSE. (meaning depression could kick in stronger.)