I get it, and I'm sorry you're going through this right now OP. It's such a shit situation to be in. People seem to forget that mental ill health is a real illness, just like the more visible illnesses, that it can cause real pain and terrible suffering, and that it can be deadly.
I had to break lockdown rules due to a mental health episode recently. I didnt mention it at all on Mumsnet, or ask for advice here, because I knew I would be told off for potentially exposing vulnerable others to the virus, never mind the fact I had been completely isolated from everyone for several weeks at that point. There are a few posters on this site who don't understand mental health issues to the extent that they sound like they would rather people die than break the rules.
Can you isolate for a week and then go and stay with someone? Or as others have suggested, arrange meet ups with friends or families, distanced if necessary? Someone vulnerable I know has been going for dog walks with a family member who lives in a separate household. They walk 2 metres apart and chat.
Other than that, don't know what else to say, except I hope your mental health improves and that things become more bearable. Even though it feels like it sometimes, this won't last forever.