What would you do if your sister wore your underwear?

Alexandra • Graduating this year with a bachelors in psychology. Then med school. In a loving relationship of 6 years. Not TTC! ❤️❤️
I just cursed out my sister because I have been noticing that my underwear count is going low. I looked in the hamper and I found MY underwear that I have not worn and have not taken the tag off in there. 
Idk if I'm wrong but I have never suffered from bacterial vagionous (don't know how to spell the word) but I was diagnosed with it like three weeks ago I bought new underwear, and went to the doctors it went away. this week it happened again and I now   Find three of my thongs inside her drawer after I wore them. 
That's disgusting and when I confronted her she denied it. Like why the FUCK are you wearing my underwear? I cursed her out and she blocked me like we don't live in the same house. 
My sisters lazy she doesn't work she has an 8 year old and lives in a house with my parents and her daughter and my brother she hasn't worked in 5 years and she sleeps all day. She's a constancy disappointment.
Am I wrong from cursing her out.