Hi there Ilovehersomuch, I read your post and wondered how you have got on. I feel so much empathy for you and your partner as I have been through a similar experience and know how hard it is to deal with. My partner went through a serious depressive episode and attempted suicide on a couple of occasions.
The space, the not wanting to be physical is all part of this and it can be heart breaking for the partner, but your girlfriend is clearly going through hell as well. The only advice I can give is to give your partner the space (physical and mental) and emotional support to deal with her illness. My girlfriend took medication for around 6 months and this was another roller coaster and I would say from my experience not advisable. Professional counselling and therapy is the best path in my opinion.
The main thing I have realised is you cannot solve the problem (as much as you would do anything to), look out for your own needs as well as your girlfriends, respect yourself and don't feel bad for offering help - it may not always be taken but don't take offence if it isn't.
Give yourself space, stay healthy, eat healthy and keep your mind active as you too can sometimes start to feel depressed if you are with someone who is having a depressive episode. Also always remember the way you see the world is not the way someone with mental illness may see the world, your mole hill can seem like Mount Everest to someone else. Listen to people but don't judge.