You are a good friend. You are concerned about her, and you want her to be happy.
Really though, she knows already that this guy cheated on her. And you have listened to her already many times. You have probably already agreed with her that what he did made him a jerk and agreed that she still cares about him.
What she really is doing is putting the monkey on your back so she doesn't have to deal with this.
Maybe she is doing it to talk herself out of it. Maybe she is relying on you so you can tell her what to do so she doesn't have to take responsibility for any course of action she takes. Maybe she feels so betrayed that she has to tell the world how hurt she is. Maybe she is testing your loyalty as she doesn't know who she can trust anymore.
Whatever her rationale, just stop listening and reacting to it. It's not your choice, you have already talked and listened enough on this subject.
Even if you don't like the guy, even if you don't like what he has done, if you keep listening, that relationship is now your relationship....
...Cut the cord. When she brings it up, put the monkey back on her. Ask her what she would do. Or just listen for a bit, then change the subject. If she keeps it up, let her know definitely that you are not interested in listening to it. If she pushes you, just walk away for a bit. You certainly wouldn't pressure a friend that way.
And for goodness sake, don't say that you always thought he was a player. What the heck does that have to do with anything now since he is gone, and it won't help her out knowing it after the fact. He has already displayed who is.