She won't be able to just 'get over' her depression.

This woman needs psychological help and until, and unless, she is willing to seek help she really shouldn't be in any relationship. There is only so much you can do.

Is she on speaking terms with you now? The only thing is to ask her to seek help. You can definitely support her through this... and hopefully it could then work out between the two of you. However, if she refuses to get help, I think you would be wasting your time hanging on to her. Your love would not be enough for her. She needs professional help, first and foremost.