Hi, i have never posted on a board before so please bear with me.

I have been with my fiancee for just over a year now and we have some major problems, im looking for some advise on what to do.

She had a problem in the past where she would cut herself and this is happening again. I beleive she suffers from depression, she get sad for no reason - she told me this it is not my opinion, i beleive that there must be a reason but i have been told crying and feeling sad for no apparent reason is a classic sign of depression.
I have tried to get her help, she will not accept it, i can get her to admit she has a problem, i have even managed to get her to agree to get help but she awlays stops short of actually getting any. I convinced her about 3 months ago to go to the Gp and talk to him about it, he prescribed her an anti-depressant but they are still sitting unopened on the self and she refuses to take them. She says she does not want help. I try not to keep pushing it with her because she gets withdrawn and pulls away when i try to broach the subject. I dont want to push her too hard for fear that she will leave and not have anyone to turn to and may do something drastic.
She has in the past set plans in motion the commit suicide but contacted me at the last moment and i got her to stop.
I believe she needs help but i dont know how to get her to actually go and get it.

Every couple of months she will swing downwards and tells me she does not love me or she is not sure she loves me, and yet she stays and does not leave. I believe this is due to her depression but i am not sure, part of me thinks that if she does not know if she loves me then she must not.
I have never wanted to force her into a relationship she does not want, it is hard for me beacuse her telling me constantly (every month or so) that she doesnt want to be with me hurts. She has stopped wearing her ring now.
She always ends up saying she is sorry and she does love me, and wants to be with me but after a year of this i dont really know whether she is comming or going. It is very hard to live day to day not knowing whether today will be the day she leaves.
She has left before but came back a couple of days later saying that she did love me.

Sorry for the mismatch of problems and explainations but i just dont know what to say.

How do i get her the help she needs? How do i stay in a relationship that is emotionally abusive to myself? What do i do?