Overprotective Mom...

I've been sexually active for a whiiiile now. I'm 16 and have basically had to educate myself on STIs, birth control, healthcare, etc. because my mom is super overprotective (tbh she's also terrifying). I'm not reckless. I plan accordingly and practice safe sex every time. Every time she asks me if I'm sexually active, I completely shut down and deny it. Either way she says she'll never trust me again and she'll see me differently than "the perfect daughter" she has now. I am so compelled to tell her. It's sad and exhausting to keep this from her. We're really close and I don't want to ruin that. There is so much at stake. How do I tell her? Should I? Any advice? Anyone else with scary parents? HELP!