[ Removed by moderator ]

I want to preface all of this by apologising for any grammar errors, english is not my first language.
So I (21f) live in my parents apartment for university together with my cousin (20f). Around two months ago she started dating this man she met on tinder who, sometimes, comes over and sleeps here. Two days ago he came over like usual and eventually, late in the evening, my cousin came to me and asked for permission to let him sleep here as well, to which i agreed only if he left first thing when they wake up after breakfast. The night passes and I wake up, then hear them having breakfast and go back into the bedroom. After 2 hours i text my cousin and ask her when her boyfriend is leaving, to which she replied that he wanted to order some pizza and eat it here. To which i again agreed but told her to make him leave after the pizza; mostly because i wanted to take a shower and honestly didn't feel comfortable enough to take one with him in the house (we're not very close), plus i had to take some underwear and clothes to change from the bedroom, where they stayed constantly. After another hour or so I see that he hasn't left yet, while some friends were supposed to arrive to my apartment in 20 mins to study for an exam, so I texted her again and let her know that I wanted him out of the apartment before my friends arrive. She asked me why I didn't want to take a shower and told me that she could bring me some clothes, to which i replied that i was not comfortable to take a shower with him in the apartment and that I wanted to wait for him to leave before taking some clothes, to which she replied "you can wait for a long time" (the translation doesn't really fit much but the original phrase was "asteapta mult si bine" in romanian). Honestly that made me angrier than the whole situation and I felt very disrespected, especially since me and my parents let her live here without making her pay rent (it's a pretty expensive city), so i texted her back saying "ok, but he won't be sleeping here ever again".
After not speaking to each other for a day, today she asked me what that last message was about and we had a fight where she told me that she isn't comfortable when my friends come over (even though 1- she never told me and 2- they are also her friends) and that since it's "my house" i should start doing everything in it. Then she simply stormed off and slammed the door and we haven't talked since.

So AITA for prohibiting her boyfriend to sleep over and for saying that the apartment is mine and not hers?