How do I tell my mom I lost my virginity?

I'm an adult in my early twenties, raised in a Christian home. I recently, after a lot of thought, lost my virginity to my boyfriend. I don't regret it or feel guilty about it at all. The only thing wrong is that my mother is very pro-abstinence, and I know she's going to be disappointed with me. I don't necessarily want to keep it from her; it feels dishonest. We're very close, but she tends to severely overreact to things, and I don't want to hurt my relationship with her. :/

Any advice is much appreciated.