You're far too nice to a group of people who are clearly too self-absorbed and ignorant to reciprocate. This isn't a salaried job where you owe anyone notice.
The golden rule went out the window when the other members decided it was a good idea to steal money from you by not paying or misappropriating band funds to buy gear or settle their own bar tabs.
The drummer's wife would make me walk alone. Dealing with annoying significant others is out of the question.
I'd tell them all to screw and not feel bad at all. They will just find another poor bass player to walk over, and if they can't, screw them all still. Life is too short to deal with morons, their spouses, progeny or anyone else who is inconsiderate enough to handle themselves with so little decorum. Good luck.