Please don't tell your boss about your mental health problems. Nothing good will come of it.
I'm a boss and try to minimize my shittiness. I want my team members to take PTO for mental issues or whatever else they need but I do not want to know the details. That is for their own protection. If they need medical accomodations they should go through the formal channels, getting it properly documented so they have full legal protections. Anything other than that, sharing their personal medical information with me or anyone else at this Mega Corp^TM^ is a bad idea for them. (US-based, think about your own country's protections before considering this advice).
Your boss sounds like an incompetent asshole. Even with a empathetic human boss though, don't tell them the details of your personal issues.