I agree with the people who say do not contact her. You still care for her and she will probably not feel the same about you.
I was in a similar situation I was with a woman for 6 years, who I wanted to spend the rest of my life with. Who about 3 years in to our relationship I realized was in a fight with depression. I asked her about getting help that drove her further down the hole. Things got so bad she could not get out of bed or do anything. Then she started getting help and decided to move. It had been a year and a half and she came back to get her stuff. I realized how much I loved her still. But she could careless about me and told me about some of her relationships sense she left. She is still in the same cycle she was in with me. That visit was crushing in so many ways. She is still the most amazing person I have ever dated, it will never work until she gets some real help and not just hear what she wants to.
Good luck! I still feel lost and not sure what to do. We had so much of our future planed out.