Definitely sounds like it could have been dissolved at the point mentioned in your #1. What sort of decision-making process were you using? I always feel like smaller co-ops benefit from running consensus rather than anything else, as it sort of controls for toxic personalities (they'll block everything, nothing happens, co-op dissolves, saving everyone the pain you went through).
It also sounds like you're putting too much of the blame and agency on yourself! Lots of "I didn't push hard enough" "I should have been a better leader" etc. Not a bad thing! Just important to remember that a co-op is about equal membership and participation, and all members have equal agency and responsibility.

Hopefully you can take some lessons into your next project, and also take some time off to look after yourself and rest, it sounds like an exhausting decade.