How do I deal with a best friend who is now an overcontrolling roommate and still be friends afterwards?

Living together can be very difficult, and doing so has ruined plenty of good friendships.

You say that the two of you have been fighting, so your friend’s certainly aware that things aren’t going well.

Could you approach her and say that you really want to talk with her—as friends, not as roommates, and with no accusations or recriminations? If she’s agreeable, you could tell her that you love her and cherish her friendship, but that your living arrangements are quickly destroying that relationship. If you’re both still capable of being calm and getting along—even if only a brief while—you can mutually decide what to do next.

Welcome to marriage. You have to learn to overlook each others peccadilloes. Sit down and discuss the areas where you are unwilling to compromise and the ones you can cut the other person a little slack. If you can’t work out some kind of mutually respectful agreement you should stop living together before the relationship is dust in the wind.

Someone has to be the alpha.

I like @Primobabe‘s answer. Set up a discussion, preferably on neutral territory (go out for coffee—keeps voices down too). Tell her that your friendship is too valuable to let it keep eroding this way so perhaps you need to move out. Let her know your goal in moving out would be to preserve the friendship. Tell her you will give plenty of notice. Perhaps, if she wants, you can help find a replacement.

Now for the hard part. You can do everything right and the friendship can still be damaged from your time living together. If that happens, give it some time and space. Perhaps, in time, your friend will get over it.

I only see one way and that is to find a different living arrangement. Move out.

@YARNLADY There’s no question that these two people shouldn’t be living together. It would be nice, though, if they could salvage their friendship and move on without rancor or bitterness.

Move.