I have worked in a group for two years where I also had problems with my supervisor, these were partly due to me, partly due to him, but in anycase our co-operation did not work very well, so I left and found myself another supervisor for my PhD studies. My relationship to my previous professor even got better, because I believe, I was relieved of my stress in my relationship with him. This kind of personality conflicts are very common in any kind of environment, where you need to deliver consistently...
But after reading your post I got the impression that your problem is a lot more of a personal problem. I think it is not only due to the character of your supervisor or how she treats you. Many people have problems with their bosses but your reaction is a bit outside of the usual range of reactions. It seems you have a hard time with stressed situations and these are unfortunately situations which you cannot avoid in life from time to time. It also seems that you show these rather certain behavioral or psychological patterns in these situations. You also mention these patterns are not showing themselves only with regard to your current situation but are recurrent. These give me the impression that your perception/interpretation of the outer world is somehow pushing you into this hole of destructive state of mind.
My advice would be: please seek professional psychological help. Psychology is not the most exact science but there is a lot of accumulated information in that discipline, which can be of help to you. It can help you to transform your perception of the facts and see light where you have seen only dark before, see hope in the future, whereas you feel deep in a dark well with no light reaching you and no ladder to go up. It can help you break those destructive thinking patterns. Communicate more with friends, family whoever you have around you. other people have gone through similar situations, I can guarantee that. I also took therapy for multiple years in my life and also during the time I was working with my previous supervisor. From my experience it definitely helps. Also I don't know how much the university councilor can help you, I would rather ask the councilor to give you the contact of a proper therapist since your problems seem to be transcending the usual student-supervisor conflicts. You do not continue playing basketball with a broken leg, so first keep your mind healthy to be able to use it for science.
I believe if you seek professional help and come to a more peaceful state of mind most of these problems you have mentioned above will be solved automatically, or will not seem to be problems at all.
In regard to the comment by JeffE: I see your point, but I know also from my own experience, when you are so deep in a dark skate of mind, your interpretation of other peoples attitude gets also also compromised. I think the "problematic, abusive boss" is something more or less common in the todays world (of course, I am not trying to normalize it or saying it should be like that), but I found some of the phrases by the OP much more alarming, such as: "self harm", "increasingly suicidal", "I desperately want to...", "I was terrified for days". I believe these and the recurrent self-destructive state of mind is the more alarming pattern than the pattern of abusive supervisor. From my experience, first thing to do is to come back to a healthy state of mind, where you can judge the situation unbiased and take the right actions based on these healthy judgements.