My mother can't get over I have had sex?

[Independent]

Ahhh yeah don't listen to that Nathan guy. Clearly he has had some problems with women in the past, and he's taking it out on you. Yes you are right you are a grown woman who can make her own choices. Plus she should not be going through your private things. I always say to not get into peoples privacy because you may not like what you find. She needs to grow up and realize you are capable of making your own choices, and with that being said you are also able to deal with any consequences that may come your way.
If she is saying to you in sarcastic manner to "go get drunk and sex", it sounds to me that she might be a little jealous because she feels she can't let loose like that. So, this might drive a wedge deeper between you two, but if you just shrug it off it will build up and end up exploding some time in the future.
I guess the best way would be to remain calm and mature when discussing it with your mother. If she raises her voice don't match it. You will come out ahead if you can remain calm and respectful. It's always easier to give in to aggression and frustration, but the results are better if you don't.

I'm in your corner darliin

Good Luck to ya