My boss clearly wants me gone

If they fire you for poor performance, you may not be eligible for COBRA (I'm not sure about that) and it could hurt you you in your next search.

Look for a new job, find one, then resign.

Of course, definitely weigh in the mental health cost of staying on to get unemployment, cobra, etc. I chose to stick it out in a toxic position for ~ 11 months to gain some well earned benefits and I am happy with that choice for my situation. I did a couple of things that really helped me get through. I reminded myself that every single thing I was doing at work was working towards getting my benefits - so my work was very focused on what I was building for myself and not my boss or the company. As much as possible, I chose activities and responsibilities that I knew would add to my resume. As much as possible, I quiet quit on activities and responsibilities that would not be helpful in a job search. I started networking and looking for opportunities straight away. Every time I had to deal with my boss' BS and lies I pasted a professional smile on my face while on the inside I quietly knew I was actively working to build an exit that benefited me. It felt powerful to be holding that knowledge.

But you really have to look at what will be reasonable for you, your situation, and your mental health. I am sorry you are going through this. Working in a toxic environment and for a toxic boss can be traumatizing. I am out of the situation with my benefits intact but I am still processing the mental and emotional aftermath months later. Speaking with a therapist on a regular basis has been helpful for me.