She needs to confide in you. And there is always the option of questioning the cousin himself. I am afraid that she might feel that she was molested, or that she in fact was, and that's why she talked to a counselor in the first place. So, don't let that option down, that she actually had been. I would talk to her a.s.a.p and tell her that i love her dearly and that there is nothing that she can say that i shall not understand and that if anything happened it is not her fault. It would be a good thing if you had an example of something your own, that she doesn't know, so she get's more relaxed talking to you. You need to get to the bottom of this, find out the complete truth and then analyze what exactly happened and what needs to be done, primarily to help your daughter.
..just to add that I probably will not come to this forum anymore. And want to say goodbye to everybody. The thing is that each time I read a story like this I completely destroy myself inside. Because of what happened to me with my brother, it's like I feel responsible for every person that was ever "molested" and try to compare myself to the case, obsessing about it. And each time I get a progress of leaving the guilty emotions in my life, a new story that I read shatters my peace and I start thinking depression or even suicide again. This is not normal and it will destroy me. But I hope that those that remain will continue to help and write to all of the new ones that arrive. Cause I will never forget how much you helped (or at least tried) to help me.