Advice with Mom knowing.

So I'm 21 years old and I know that I'm an adult and can make my own choices and decisions. But tonight my mom found out that I'm not a virgin anymore. I've been with the same guy for the past two years. He's my first. My mom said that she kinda figured that I wasn't anymore by the way "I talk about him". Then she just got quite and walked out. And acted like nothing just happened and went on with her evening. Our relationship is so close, she's my best friend. And now that she knows i don't know what to say or what to do.