maybe make an agreement with him to limit the wedding night to kissing, kissing, more kissing, and then a hand job - you will figure out how to work his penis, and he will help you. This way there would not be anything in you to cry NO, right? No risk of vomiting, bleeding, pain, or some such. No risk of losing control - you will retain full control. Problem solved. As you become comfortable with this (which is still undeniably SEX), you will move on to new horizons. You can also if it feels safe allow him to touch you manually, but only it feels good.