Do I have the right to be annoyed that my roommates boyfriend sleeps over average 4 times a week?

She cut him keys to the house (without asking me if it was okay), he shows up at all hours of the day or night. He comes here for his work breaks when my room mate isnt home. I freak out because who the **** is coming into my house at midday when my roommate is at work. She thinks it makes it ok that she tells me when hes coming; it doesn't make it okay. He's constantly in her room with her printer (which I paid half of the ink for) and because he's over so much she gave me the half I paid for the ink back so now I have to buy a printer because he's over so much. She never goes to his place, he's always here.. she says its because he has work late and he cant catch a bus late. Well why doesn't he tell them to give him shorter shifts or work during the day??? He doesn't pay rent. He uses my hot water WHICH I PAY FOR so I have to have a cold shower during winter.. I'm not jealous in any way or anything like that. I pay to live here (a ******* lot of money as its 7km out of the city) , it's my apartment. Just because he's dating her doesn't mean he can lounge around here whenever he wants however many days a week he wants and even though he's in a different room I feel like he's invading my personal space. She said to me he's too afraid to leave the room in his boxers because he doesn't wnat me to see him. (I don't even think he's attractive why would I look at him)??? He doesn't even knock or beep the thing when he shows up he just opens the door with no notice; especially when shes not here.... Do I have a right to be angry?? She seems to think just because they've been going out for 2 years means he can be over whenver he wants. I feel like I am being alienated in my own household.