Be the better man?
So that the band get what they want and continue to think the way they treated the OP is ok?
My 2 cents: do the pros of wanting to do a great gig, outweigh the cons of doing a gig with people who have treated you as they have? If you choose to to the gig, as someone said earlier, I'd asked for half the fee.
FWIW I would not do the gig. Though had the split been amicable I would have.