Recognize that you are involved in a codependent relationship. Melody Beattie, the preeminent author on codependency who helped pioneer the use of the phrase in her 1986 book "Codependent No More," defines a codependent relationship as a relationship in which one or both parties involved "let another person's behavior affect him or her" and become "obsessed with controlling that person's behavior." Melody Beattie is a recovering codependent and has published over 15 books on the subject, many of which have spent time on the "New York Times" bestsellers list. Like any form of recovery, recognizing that there is a problem is the first step to solving it.
Discuss the codependent nature of your relationship with your partner. Explain to him that codependent relationships are not healthy and result in obsessive, abusive, self-destructive situations. Explain to him that, in order to progress and overcome your codependent nature, you must remove yourself from the situation. Hopefully this will allow you to come to some sort of agreement regarding the breakup.
Remove yourself from the relationship completely. Since codependent relationships center around a feeling of reliance, you must remove yourself from the relationship completely to establish that you can indeed "stand on your own." Feeling sorry for the other person or staying with her because she "would not be able to live without you" only reinforces codependent behavior.
Seek help. Talk with friends and family members about the breakup. Schedule and attend a session with a therapist or attend a support group meeting. Codependent tendencies often develop during adolescence and childhood, making their roots much deeper than the relationship you just ended. Failure to address your codependency issues and discuss them with others will inevitably lead to another codependent relationship further down the line.