Get with the good 95% of your company and start a new entity. Don't tell your cofounder about it.
New entity makes a deal with your current one to exclusively license the technology and branding, and take possession of the assets. Make the deal as one-sided as you can without your toxic CTO catching wind (and without breaking the law or giving grounds for a lawsuit in the event they do catch wind).
All new R&D goes on at the new entity. All existing staff gradually curtail the hours they spend at the old entity and "resign" here and there, all while working for the acquihiring new entity. Old entity never hires replacements. CTO continues frittering away, you can't afford to pay him, but ensure that his equity in the old firm is acknowledged and protected. At the end of some period (e.g. 3 years), the license agreement ends, everyone but CTO makes a clean break and officially works for the new firm. The old shell of a company gets folded up due to having no money.
Truman Show acquisition.