lol, this will be messy.
Look and see if both your names are on the lease. If just your name no problem.
If both, then you're equal cotenants, and you'll need to draw up a contract or talk to leasing office and get them to give you a contract for her to sign to seperate you from the lease agreement or since you want to stay, state that she's a sub tenant and then you can request she leave.
If the lease says, she's the subtenant then you can ask her to leave., evict her.
Ah, asking for legal advice in a body-building forum and getting replies from dilettantes who fancy themselves lawyers... Let's look at just
two of many things that could throw a wrench in the brilliant plan by "
youandme, Esquire":
First, anabolichalo might be living in a state in which his relationship could be considered marriage under common law, in which case, none of the above will work and could make his situation a lot worse.
Or, second, he might be living in one of the handful of states in which cohabiting couples are considered married for purposes of determining if one person can kick the other out.
To put it another way, don't quit your day job.