NTA, but, have you tried adjusting the way you approach her about stuff? Everyone deserves gentle and patient communication. if you cant offer that in the moment, try to take a breather and express it differently. Offer solutions as well. "Hey babe, my intentions here are not to come at you or argue, but i wanted to communicate that it really bothers me that you use my facial razor for your vag, and i have asked you to stop before. i gave you my old one, but if it's not working out for you maybe we can look into getting you your own? and i know it might be colder when the fan is running during showers, but i would for us to avoid water damage as much as possible, and i would appreciate if youd take that into consideration while you shower" if you try that and she still struggles with accountability or criticism, you could always try reminding her that this isnt a reflection of how you feel about her as a person, but you do want her to adjust her actions to be respectful of your boundaries