Try not to stew about it if you can, but I think it's time for a serious discussion about how the band is going to work. If the guitarist is calling all the shots (or trying to !) and you're not happy with it then something has to happen. I'd try to canvas opinion from the other band members if you can - it's entirely possible that you're not the only one who feels this way, and see if you can all have a word with him. If the rest of the band works and it's just the guitarist who's the problem then he should be the one looking for a new band, not you.
It's pointless just leaving without saying anything as far as I'm concerned, so think about what you'd like to say at the next rehearsal and see if anyone else feels the the same way and wants to raise it too. With some discussion and compromise you might be able to get things going in a sensible direction. I'll keep my fingers crossed for you.