Quarantine, roommate, and boyfriend

So my boyfriend has a grandma who is extremely at risk to catch covid-19. She has to be taken to dialysis a few times a week for liver damage. My boyfriend has not been able to see anyone except me since I am too making sure I’m not going out anywhere so I don’t expose him and pass things on to her. My roommate has been seeing this guy and he’s been coming over. My boyfriend was sleeping over one night when way later in the day my roommate said she wanted the guy she was seeing to come over. I didn’t want to risk him passing anything to my boyfriend while he was in the same apartment so I told her I didn’t really want him there since my boyfriend was there. Am I wrong to tell her she can’t have someone over if he’s here at the same day? She even said she was going to do what she wanted but Like I understand I shouldn’t be so controlling but there’s a virus going on. And now she’s saying she’s not too fond of him since he didn’t want to be exposed but I even told her I didn’t want to risk anything either. So can someone help me know what I should do or if I’m wrong?