He invited a girl to live with us without telling me!!!

i live with my fiance in a 1 bed 1 bath apartment. He decided it was a good idea to invite a girl he has never met in person to live with us for a month to save up money so she can be on her own. She is supposed to be here in a couple days and he just now told me! Told me, not ask me about it! I've already expressed my feelings to him about this situation but bc of me being me i can't tell her she can't live with us in such short notice. Ik they will end up alone together a lot bc I work 12 hour night shifts and it really bothers me. There's not really anything i can do... i just wanted to vent a little. Update: a lot of people are asking how they know each other. They met on facebook. That situation isn't an issue because both me and him have made really good friends from the internet, plus we met online. I've talked to him about this again and he went more in depth of why he offered her a place to stay. i will not share that bc its really personal to her and its just too much to type out. I've set rules and cameras. (cameras are not known of other than myself) She is not allowed inside of our home without me there and the second i find out she is she will be out. A lot of girls are saying they would leave him and im not going to do that. Unlike the rest of the guys i have been with, i fully trust my fiance. I made this post out of frustration that he didnt consider my voice. I know he wont cheat. It is the girl i dont trust