bluebicyle, I totally know where you are coming from and know how painful it is to feel disabled in such a way, and under such pressure. I wish I had some absolute solution to offer, but other than communicating this serious issue to your therapist and psychiatrist, I don't.

The following questions do come to my mind:

Is there a part of your job (duties/tasks) that you are still meet expectations on? If so, can you discuss this/these with your boss? Sometimes when ill, I have had to focus on these. Even alleviating colleagues of such tasks can be a temporary solution.

Would some kind of accommodation help?

Would a certain type of pressure help? I don't mean a negative one. I'm thinking along the lines of working in spurts and then being given the allowance of a break. Then repeat. Being accountable for "spurt" work can be the fire under the butt needed, sometimes.

Could working along with a colleague closely help?

Just brainstorming.