Roommate's girlfriend moved in unannounced...

Hi Everyone,

I have been living in the same apartment in Brooklyn for the last 5 years in a 4 bedroom apartment in which I have my own bathroom. I love living with other people and am totally respectful of boundaries when it comes to multiple people in a dwelling and am super clean when it comes to shared spaces. I have lived with one roommate in particular for the last 5 years and we are like brother and sister. We know each other's families and friends and are very cool with one another. He started dating a girl from CA who I love and also became good friends with. She decided to move from CA and needed a place to stay until she could get a new apartment as the apartment she was supposed to have a room in fell through and she had already moved her things and bought her plane ticket. She stayed with us in the 4 bedroom for about a few months and found an apartment in a neighborhood nearby. She still came over, we hung out, travelled together, and always had a good time. It was nice to finally have the apartment back to just being those of us who pay rent (mind you I am the only one on the lease). March rolls around and I came out of my room to find that she had moved back in unannounced and none of the roommates knew nor agreed to it. Her belongings are in suitcases and bags taking up space in our living room as well. She said it would be temporary as she was looking for a new place after her trip to Thailand with my roommate and would move out soon. It is now the latter half of July and I feel as if both she and my roommate have been taking advantage of the rest of us in the apartment and there is no respect for the rest of us who pay rent and utilities. She also cooks everyday and leaves a mess (grease in pans and on the stove, puts food in the sink and doesn't wash dishes and they are always in the living room watching tv and we can't really use it because they are always there - they are freelancers -throws food in the recycle bin, and also invites her friends to come over without letting the other people in the apartment know, including inviting a friend from LA to stay overnight and didn't tell anyone). Am I right for feeling really upset at the situation? She doesn't pay for utilities or rent as far as I know. She also has invited her friends over to hang out and has had friends stay overnight from out of town and neither of them said anything to us or gave us notice. I've talked to my roommate about people staying at the apartment for free for long periods isn't cool before but I just feel like he also has allowed this to go on. Should I charge her rent? Or just ask her to move out? I'd prefer the latter as it's already 4 of us but I don't want to strain the relationship as they are people that I do care about. I'm all for helping people out in times of need but I don't want to be taken advantage of.