My Christian mother in law is pushing for her pastor to officiate the wedding. I am pagan. What to do?

I have not told her about my faith, seeing as most Christians equate paganism with satanism. Which of course is ignorant. I do not want to upset her. I tried stratling the fence by telling her I was going to get a Unitarian officiant. She just told me "Oh no, you don't want that....pastor so and so will do it." Umm no lady. Should I come right out and tell her, be coy about it or what? I am having a pagan unity ceremony no matter what, I am just toning it down out of respect to everyone. It is also scaring me that I am going to raise my children with the pagan faith, but would like to expose them to all religions, including hers, so that they can decide for themselves. Her and I get along so well, I am scared this is going to come between us.