just ended a lesbian relationship but want visitation with her child.

There are many questions, and this area of the law is in some flux recently.  From your description, I presume that you are not on the birth certificate as the "other parent" -- although you could be after last year's St. Mary decision.  We would need to know all of the factual details -- biological and legal, who actually did what in what order, to evaluate whether you have a viable claim to either custody or visitation. Please put together a timeline (an explanation for doing so can be found at http://willicklawgroup.com/consultation-policies/), and then consider scheduling a consultation appointment with this or another office of a family law specialist.