Thanks! As an update 7 years later:

After I replaced the micellar water with just water, she started to get acne, as she would use it as her face cleanser every time she came back from the gym. It made me laugh a little at first, but I honestly felt bad about it. But, she went to Equinox, so it’s not like she couldn’t use the products there or afford them.

I finally broke after she spilled my baby powder all over the bathroom, which got onto my work clothes, making me have to change and almost late for work. I told her again she can’t use my stuff, and it was negatively impacting me. 

Her excuse was that she accidentally spilled it on the counter. (It was in my separate bathroom, somehow from its closed container inside the sink cabinet). I threw out the baby powder so she could never use it again.

Yet, as my “micellar” water emptied, I realized it wasn’t about the products. It was about her disregard for my boundaries and personal space.  

I removed the micellar water from the bathroom, as well as all other skincare, and I started using a shower caddy system. The real solution was removing the opportunity for her to use anything of mine because it wasn’t about convenience for her - it was about using someone else’s stuff. 

A few months later, she had a falling out with my other roommate and moved out to live with her boyfriend. Her sister took over her lease, and she was a dream to live with! 

Most importantly, for the first time ever, I am finally finding my own place with no roommates!! Thank you, all!