It sounds like it has the potential to be a can of worms if there were ever a claim.
I can't answer any of your "why" questions.
The situation between you and your brother is dysfunctional and your options are limited to bad and worse.
1 - Find yourself an independent agent and buy yourself a policy. If you don't care what happens to the property just buy a liability policy in your own name for your own protection against lawsuits.
2 - Force the sale of the property through a partition action. You'll need a lawyer. You'll pay a lot. Your legal costs may exceed whatever your share of the proceeds will be.
3 - Quitclaim your share of the property to your siblings and walk away from the property and them. They are already lost to you.