Retreat and re-group.

Looking at the others as they stare at you with horror, you quickly decide there's no point in trying to explain yourself. Looking at the disgustingly sincere-looking appearance of terror on Derek's face, and at Amanda's own shocked expression, you know there's no way she's going to believe some guy she just met yesterday over the man that's been her boyfriend since they were teens, even if you did already save her two or three times already. Still, looking at her eyes, you also don't think she has it in her to shoot you in cold blood, either.

Meeting Amanda's gaze with steady determination, you quickly call out to everyone, "I was framed! Watch out, that's not Derek anymore!" You might not be able to convince them now, but hopefully you can plant a seed of doubt in their minds. Enough to put them on guard.

With that, you turn and run off into the woods. As you guessed, Amanda can't bring herself to fire. However, after a few seconds you hear Maya yell out behind you. "Here, give me that!"

Shit... sure enough, bullets start smashing into the trees just a few feet to your left and right as Maya pulls the gun from Amanda's hand and starts shooting at you herself. Fortunately, you're already far enough into the tree-line and underbrush that she can't get a good bead on you.

You run for several minutes into the woods, until you're too exhausted to keep going. The good news is that you've managed to get away from being shot. The bad news is you're now deep in the woods and not 100% certain about your position relative to the camp. And even if you could make your way back there, everyone thinks you're a demon. Not to mention you have no means of actually fighting the one demon that actually is there. Not to mention he'll probably be busy converting more of your comrades into fellow hell-spawn as soon as he gets a chance.