Need some help

I'm 19 and have decided to leave the church. However i'm having trouble actually following through. I have my letter all typed up, almost ready, all i need is my membership record number, and the date i was baptized. The problem is that i need to ask my mother for this information. She already knows that I don't believe in the church, I told her when she wanted me to start on my papers. I just don't have the courage to tell her that I'm leaving the church, i know it will hurt her, and the majority of my family, but i still feel the need to separate myself from the church. Any advice on how to come out as an Atheist?

Thanks guys means a lot.