I need some opinions from both girls & guys about a fight my g/f & I are having.?

About a month ago i put up a question about what to do about a homeless, druggie friend, that kept crashing at our house (her friend). Well, we came to the agreement we would help her best we could without supporting her. (she doesn't want help, she wants handouts). Wouldn't u know it...come a month or so later, she's stayed at our house about 5 times. Every other day I come home from work to hang out with my girlfriend, she's there, and we don't get to hang out. I am very protective of my house and belongings. I have asked my g/f if she would stop allowing the friend to (sleep) in our house while we are not there. (she used to give the girl her credit card to go up to the store to buy her cigarettes). Today i come home and she's asleep on the couch. WTF??? I hit the ceiling and got mad at my g/f. I didn't blow up or say anything I shouldn't have, but i did say if I say her again at our place, i was gonna get her car towed. Don't focus on my response, but HOW BIG OF A DEAL IS THIS??