Probably if there is not an agreement possible with your current PI.. I guess not all of them are empathetic or willing enought to tolerate this kind of problems, it's not fair, like, they probably wouldn't act the same if it was not a mental disorder but other kind of disease, but world is not generaly fair.. it would be the best way for now to try to find a compromise with the department chair and former PI to let you finish but probably without his personal involvement. But not just letting you out, with nothing.
You have your rights to be treated fair, if possible, but trying to force a PI to work with you would cause more troubles for you, if he really doesn't want to have anything with you, he has always many ways to complicate your life, to create you problems.
So siting there with him and some higer authority saying, "OK, I got it, you don't want to deal with me any more, all right, I don't want cause you any more troubles either, but at least help me to finish it in short time, and you will never hear of me again". Maybe they will be more open to at least find someone who can be your new PI and who can help you finish, than trying to force it on him.
You see, having a mental issues is not a same handicap as having a physical one, while dealing with people, but worse. A guy without a leg.. it makes people feel sorry, and he is arguing the "normal way", any anti-discrimination actions have better chance to be sucessful even if they attack someone.
With a mental disorder however, situation is different.. especially if you have some problematic aggresive history and erratic behaviour.. this doesn't cause empathy, but rather fear in common people. And if you deal with them in person, they will always look at you like you are the "crazy" and any arguments are hard to push.. and if you actually do behave different at that time.. Filing some kinds of complaints aginst your PI would only IMO worked enough if you have someone covering your back, a lawer, organisation that offer this kinds of support.. but that you probably do not want, since that shows you even more "incompetent". This is useful for mentally ill people whose rights were abused, and they can't fight back.
So for you.. compromizing to find a more supportive ground and trying to look as much "calm" and "normal" as you can during that, eve when you are rightfully angered. Your behaviour when you are labeled like this is always percieved through a diffferent glass now.
So, try to find some quicker and easy way how to finish a degree, and then you will have time to think what next. What kind of enviroment you are suited for and what you need. If you will get some sort of progress, surely the depression will be more contained in your theses and not in your life. ADHD (which I guess is the english abbrev for TDAH) is a lifelong frustrating and complicating think, but it can be managed, with some arrangments.
I wish you luck. If not for anything else, then for the fact that I myself have struggled through some more serious mental problems during my Ph.D. but I had the luck of quite supportive PI, at least in that, that he did not throw me "out from the ship", tolerated long time of a work non-exactly-competence when I had just too many other things to deal with and the great deal I had with finishing the thesis (eventhough, that is another story.. at that phase he WAS pretty pressing and drove me to a point of absolute despair at the moment of sending him the finished text, that I just felt I don't care about anything anymore and could see no future, and could just hang myself stright from the balcony.. but lucky for me I did'n not care that much about it either, so here I am, still..).
It is hard, but if you can still hold together, you can still find a way how to finalize things, don't go too much frustrated, or to much angry, or selfpittied, for that is not helpful, don't give up, fight, but fight smart.