Relationship headed downhill

My girlfriend moved in with me about 18 months ago. She suffers from Relapsing/Progressing (aka Chronic Progressive) MS, Lupus and Crone's disease. Our relationship is near the breaking point partly due to her conditions, but maybe also regular relationship problems and partly by feelings on both our parts engendered by the conditions. I have bi-polar disorder, which is fairly well under control with medication, and Epstein-Barr syndrome. We are both disabled and spend most of our time together at home with her brother who also lives with us.

She walks and can do much to take care of herself, but her hands are so painful that they are of limited use. The frustration of not being able to do what she once did and of being dependent on me is great and comes out daily, as anger. Traditional medicine has caused more harm than good, so she started treating herself through diet and herbal supplements, with some success. Her condition has gotten much worse since she moved in. She experienced numerous spells of what appeared to be strokes, but were determined not to be by a well respected stroke specialist. The sole MS specialist at the same medical university told her the opposite and said she probably didn't have MS (she was exhaustively diagnosed over 20 years ago). She has had many similarly bad experiences and views the medical community with suspicion and disdain.

Recently she started displaying irrational behavior which lead up to a serious suicide attempt. She was in critical care for a week followed by about 2 weeks in the psychiatric ward of the hospital. The psychiatrists there had no idea what they were dealing with; she was experiencing delusions, hallucinations which subsided during her stay. While she was there I did some research on the psychiatric effects of MS and found that her behavior could possibly be explained by MS lesions on the brain. She was released on the condition that she report to a psychiatrist weekly for some period of time. She has visited this psychiatrist twice now and the psych says that she believes that psychiatry has little or nothing to offer her; this is a neurological problem. We have an appointment with a neuro-psychiatrist in February, but are trying to get one sooner. My GF says, correctly, that there is no reason why the irrational behavior or even suicidal behavior couldn't come back, as we don't know what it is or how to treat it. She denies being afraid of anything, but I know I would be if I was facing the prospect of losing my mind.

A little additional background: Soon after she moved in, my GF began complaining that I said mean things to her and was insensitive. I don't doubt that I said some things which were hurtful, but purely by accident. Some types of speech I now know she finds demeaning (we are both highly intelligent and I am used to explaining things to people) and have worked to change, although she says I haven't improved. She becomes very angry if she perceives she is being ignored, even if it is because I am working around the house and yard etc. When angry or hurt she responds with bitter sarcasm, which I find very hurtful and do not respond well to. Since coming out of the hospital, the accusations of mean speech and being ignored have increased. We can hardly talk without it becoming an argument.

As I mentioned, her brother moved in with us in October. I like him and was glad that I would have some help with some home repairs and with my GF. Unfortunately, while my GF was in the hospital, his BP went through the roof. He's already had 3 heart attacks and now has congestive heart failure. So he is very limited in what he can do. He does what he can, maybe more than he should. Neither of them drive and between the three of us, there are several doctor's appointments every week.

I do tend to isolate when depressed and also focus my mind on mathmatical and mechanical puzzles to avoid thinking about problems. That is my "happy place". So she is right that she is not getting enough of my attention since coming from the hospital. I may also be distancing myself to protect myself emotionally in light of the suicide attempt. Even today she said if she had a gun she would shoot herself.

She thinks I want her to leave. Maybe in a "grass is always greener on the other side of the fence" way I do, though experience has taught me that it rarely is. I have a great deal of trouble expressing my feelings to her as they are confused and because I don't know what will offend her. I'm feeling guilt and anger and need a break from the stress.

There is much more to all this, but I have already asked too much of anyone who has read this far. Any thoughts or support anyone could give would be greatly appreciated.