I believe I did kill Dror Ragzlin in a similar situation, although I waited until Minthara left the temple and then I went and fought him. I even killed Priestess Gut for her tadpole before that and no one cared.
After fighting Ragzlin all the camp will go agro on you but it shouldn't make Minthara hostile if she's already out.
I you're not in honor mode I'd say make a save just in case things go south.
