Remove yourself from the living environment for a few days to give yourself some time to quell any emotions you might be feeling toward your ex-girlfriend. Spend a few nights at a buddy's place or go visit your family for a weekend. Make sure that you have a calm head, are free of emotion and are completely sure that you are making the right decision.

Communicate with your ex-girlfriend about your feelings about the living situation. Let her know that you respect her feelings, but you just need your own space. If it is your own home, remind her that although she has been staying there, you own your home and you request that she give you some space. If you share the home equally, communicate with her about why you believe it is best for her to move out and find a new place.

Help her pack up her things and make sure that she doesn't leave anything behind that might give her an excuse to come back. Give her a few days to make other living arrangements and do everything that you can to be kind and supportive. Remember that you once cared deeply for this girl and that you should always treat her with respect.

Contact any authorities necessary if things get out of hand or your roommate still refuses to leave. Speak with your landlord if you rent a home to find out what your rights are if you share the place with your ex-girlfriend. Call the police and file for a restraining order if your ex-girlfriend is refusing to leave your property.