Did talking with your wife about this feel like something positive? It sounds like something positive from what I'm reading. Even if you don't agree on the impact of the A at the moment, it sounds like a good place to be in that you guys can talk about it, and also that she told you why she's feeling depressed.
Do you think that keeping on talking with her will help you guys? It really seems like it could. I think if both of you have hope that it WILL get better gradually, then you can make it, if you want.Find peace. Or sleep on it.
Infidelities are like icebergs - they may take many different shapes and sizes, but they all damage your ship.