GF and I were dating for 2 years in college. Everything was perfect. This fall I came down with deep depression. I would have anxiety attacks about what I felt was a hopeless world and break up with her. Happened probably 8-10 times. I was living in Colorado, she in Chicago. After the tenth time breaking up with her she had enough, said we were broken. I cut ties from her for two and a half weeks. I receive an email how she misses me and felt that because I wasn't doing anything about the depression that she was becoming an enabler. I have since gone on antidepressants and therapy. I have advanced my life (171 LSAT). When we were together we talked about marriage weekly. When she broke up she said she didn't see it as the end. When we talk about it now she said she loves me and that it is still her "dream" to marry me, but she needs to see changes. She needs a "grand gesture." I am not sure if it is the depression, but I still feel like it is over. When we talk on the phone, we fight every time due to my depression. I have since told her I need to work out the depression before I can talk to her more. I have set new years eve as the target date. I hope I am right by then. Would surprising her on new years eve be a horrible idea? Do we still have hope?

Depression can be a very hard condition to get over.. I commend you making the commitment to get over it and get better.I'm not sure how severe your depression so, I don't know if New Years is a realistic date or not.
You may still have issues with depression and she could have fully moved on by then. Getting better should be your main focus now... your whole life depends on it. Relationships, girlfriends are just one aspect of your life.

Depression can be very bad depends on the severity of it but it can treated well off you have set an target for yourself and that's really great so help yourself rest all can be taken care off once you are out of it if she loves you she won't go anywhere and even if she goes that is not your priority for now to get well and better is most important.. love and all will come back to you and these are all secondary matters getting better should be there on your priority list.

Setting dates, and deadlines is not helpful, as it may take longer to get yourself right.

Solve your own personal problems first, then see what happens later. One thing at a time.