If I might add my two cents about the divorced parents that hate each other, I think it's best if you remind them that the wedding is about YOU and not THEM. Of course you can't just say it that way, but I think you need to try to find the right words to tell them that they have to, if not bury their differences, at least put them aside for a few days to help make this the happy time in your life you know they want it to be for you.