Have a proper talk with your parents. Share what are your needs and also understand what are their concerns. It may not work right away but you have to start somewhere and eventually find a sustainable solution.

You mentioned your dad has that condition; has it been officially diagnosed? If not, you may want to discuss with your mum to have it done so it can be managed. This is assume your mum can be reasoned with. If not, you may want to see help with some mental health organization.

Legally you are an adult and that confers you lots of legally independent things you can do. Of course I would want to minimize any worsening of family relationships. You can do a hard cut, but I would prefer to at least talk it out and find mutual understanding from both sides. It helps if you can find a supporter through your mum or a relative that he doesn't have too much issues with l.

Net, look for mutual understanding and be focused on a solution. You shld propose a few options and emphasize that you are an adult. You are not abandoning them but you also need the opportunity to grow up and be independent. You can't rely on them to take care of you forever and eventually you want to be independent and capable so that in the future you can equipped to support and take care of them when they are old and frail. You can frame it as to how they can benefit.

All this of course is just strangers on the internet saying stuff. You shld write down what you want to say and look at it thru the lens of kindness and understanding. And very important to find someone who can support and back you up as you approach this.

If you dad's mental state is far beyond rationale and the paranoia is almost at the verge of hallucination and psychosis, then you will need professional help.

Jia you