ah, fights with mom. I had them constantly from i was 16 till i moved out when i was 18. It was hell on earth. The first time my parents found out i smoked hash, they did not get mad. But 3 weeks later they found out i smoked siggies, and i was grounded for god knows how long.
Later, i was busted for smoking hash many time, and mom always freaked out. We were fighting all the time, and whatever i did wrong, the hash was always the reason. My dad is a bit more liberal, and he got in the middle of us. I feel really bad for him now, because my mom was a bitch, and i was a huge asshole.
Now my mom thinks i have stopped smoking hash, but my dad is a little smarter, he just dont care as long as i have a job and so on.
If she continues to search trough your stuff all the time, start to do the same with her stuff. And she will understand how it is to have no private life.