It's a quandry, I get that. how can you trust an evil priest that you won't be harmed? Then again, what does he have to gain by lying to you? He has the clear advantage here.
Then again, his boss is a sicko torture expert, so he could just be screwing with you. And who willingly surrenders here? Tough call, I feel you.
Aside: Midge is dead. He was badly hurt and burned up life force casting beyond his capacity in an effort to save y'all. He's at negative HP, and HP lost by doing what he did cannot be magically regained. He'd need an immediate heal spell to stabalize him, and that's not going to happen in time.
He did understand what he was doing, whcih is why I gave him a final line. I know, nobody really mourns what has essentially been an NPC, but there it is.