@jim 1968,
It sounds like a Facebook glitch. You are not supposed to be able to be in a relationship on FB if you do not have the other party consenting. That is, FB relationship statuses are bilateral.
Go back, refriend her (if you can), make sure to delete her as your girlfriend, and then unfriend her again. If that's impossible, ask a mutual friend to ask her to delete the relationship status. Explain that it's a software glitch and you're sorry to be reminding her of it, but there it is and you both know it's not the case anymore.
I'd also suggest deleting your cookies and checking for spyware, to be on the safe side. You might be seeing older, incorrect information because your PC is compromised.