Oh yeah, I was being dozy and muddling PIP with ESA, sorry.
Am I correct in thinking that at least hypothetically it should be possible to live off just ESA and housing benefit? Perhaps you could work with your CPN's replacement on budgeting and ways to save money so that you feel more confident managing without PIP. I'm not sure exactly what your disability-related extra costs are that you were previously using PIP for, but I wonder if other services or charities might be able to help with those things.
I know this feels huge and the extra burden of this overpayment business is incredibly daunting, but I'm confident that you'll be able to get through this and adapt to the change without having to lose your cats.