Husband thinks I'm cheating. I'm not.

My (40F) husband (47M), together 11 years, married for 8 years, has convinced himself that I'm cheating. The thing is that I'm not and never have. His "proof" is absolutely bonkers. Dirty laundry triggers him. Like he thinks any kind of stain or wet spot on dirty clothes is where I slept with someone else and that person cleaned themselves up. Except that's completely irrational because for this to have happened, my husband would have had to have been home at the time this supposedly happened. He's convinced that the neighbor is watching the house waiting on him to leave. He's cycled through thinking this about four different houses, including one with that belongs to a single mother with two daughters and one that belongs to a couple in their 80s. He thinks that I have someone in my car with me on the way and from work. A couple of months ago, I hit a low lying branch and he thought that it was a car door slamming (i.e. me dropping someone off). Even showing him the dashcam footage of my hitting the branch and then listening to himself flip out didn't convince him.
On my end, I don't go out by myself. I can account for every minute of my day. I go to work and I come home. I leave and arrive at the same time every day (which he has also cited as proof before because "no one is that consistent"). At this point I feel like a prisoner in my own home because going in the front yard or getting the mail is me obviously putting on a show for the neighbor so I try not to go out more than neccessary. I have stopped suggesting going out in public because he always accuses me of looking around like I'm looking for someone. It's exhausting.
I suspect that this is a side effect of a medication that he's taking. This started about two years ago when he started taking it. That is also about the time that he also started "collecting" rocks and then started trying to convince me that the rocks fit together like puzzle pieces and made Native American statues. So, I understand that this is mental illness, but the constant accusations of infidelity have obviously caused a lot of issues. He says he can't help verbalizing his thoughts, but his thoughts are mean and I get made and that leads to screaming matches. And that's affecting my kid.
At this point, I'm so close to asking for a divorce, but I really do love the person he used to be and quite frankly since he hasn't held a job in three years I can't afford to maintain two households.
Tl;dr. Husband is having irrational strong delusions that I'm cheating. I'm not. Don't want to/can't divorce him. Don't know what to do.


Source.