Reddit, have you ever had to come clean to your parents? Any advice?

Sorry for the wall of text, but I need some perspective. I'm 21 now, but I have basically lived a lie in front of my parents since I was around 15. Just some background, they are both very conservative. No sex before marriage, no alcohol, etc. You know the type. Now don't get me wrong, I love them both. They're my parents, they've been there for me, provided for me. They're the perfect parents, but they don't get me. A huge reason why I've lived such a lie is because I don't want to let them down, and I keep so much from them out of respect. I've chased women, drank lots of alcohol, smoked lots of cigarettes, tried a few illegal drugs, haven't been to church in years, etc. I moved out at 18 for college, and it's only gotten easier to live the life I want, but not one they would approve of. I have been with my girlfriend for three years now, and she's just like me. We took a trip last week and stayed in a hotel together. Nothing new for us, but I let my parents know we were getting a hotel alone together just to see how they would react. My father was understanding and didn't make a deal out of it, but my mother gave me a long speech about putting myself in "dangerous" situations (meaning alone with a female), and making decisions that weren't in line with "the way I was raised". It made me realize that I'm tired of living this lie. It's getting too difficult to hide things from them, and frankly, I'm sick of it. I want to come clean, but I know it could possibly ruin their opinion of me, and the last thing I want to do is let them down. Does Reddit have any advice for me?

tl;dr: Ultra-conservative parents don't know I like sex, drugs, and rock'n'roll. Tired of hiding it.