Dude, it sounds to me like you're waiting for someone to tell you to quit.
Quit.
I would have done so ages ago, I have quit bands purely on the strength (well, weakness) of their live presentation. It made me feel embarrassed to be on the stage, and I worried that my reputation as a good player would be tarnished, That's without the fact that the guys are clearly taking you for a ride... If the band, music, and gigs were good and fun then I would put up with it a little.
Some of the more reasonable members will tell you to call a meeting and air out all of your problems, which is probably the best thing to do. But the success of that depends on how much they respect you among other things. Again, I would just quit.
Good luck whatever you do!