How do I tell my mom I'm not a virgin?

Yailin
My mom and I have been very close ever since I was little and she always told me if I was going to have sex to tell her when I'm ready and stuff like that. But I lost my virginity in November and I still have yet to tell her. I'm just afraid that it's going to disappoint her and I also don't know how to bring it up. How should I tell her?