I need advice on talking to my mom.

I'm 15, and I have recently lost my virginity, and I want to tell my mom, but I'm afraid She'll kill me (not literally, you moms on here will know what I mean), I need help on telling my mother, cause I know she's gonna question, when, where, why and who, and I honestly don't want to tell her, cause it wasn't to my boyfriend, I was at a party with some friends, and I barely knew the guy. Yes I know, it sounds horrible but I regret it so much, and I don't know if she will understand?