First, don't get too distressed. Remember, according to Freud dreams that express fears are done so that we do NOT have to deal with their negative consequences in the waking world. In the dream you scream and snap at your friend, because you don't wan't to do it in real life. If you choose to talk to this person in the waking world, you have the freedom to speak gently with the knowledge that your subconscious has already released the stress pent up behind whatever issues you may hold.

I'm suggesting in the part about you that having her living with you is allowing you to see traits within you that you might not have seen before. As I said, every person in your dream is an expression of you. There are NO exceptions in that rule. It has to do with projection in how we perceive the world - we react negatively to some people because we see traits in others that we dislike within our-self, and we react well because we see in the other person traits we praise within our-self. You saw your friend in the dream. That means there is something you see in her that you also see in yourself. That you want space causes this internal distress where your subconscious holds the connection between these traits in you and seeing your friend and it asks "If you want space from your friend, you must also want space from this part of yourself." (( The subconscious is big on generalizing things.))