Are you sure she has not cheated? It seems like that is on her mind, unfortunately. Dang, the only thing I can tell you is to pray about it. I'm so sorry, brother!
Also, what was her point in telling you that? So she doesn't find you attractive...was there a reason for her to tell you? Does she want you to change or what?
I mean if I was married but wasn't physically attracted to my husband, I don't think I would tell him that. It's rude. I think if someone really loves someone, they would be willing to accept them no matter what. This could be if the person is fat, ugly, too skinny, full of acne, bald, short, hairy back, scarred...whatever. Love is pretty much blind.
I'm not saying that looks don't matter in a relationship, sure they do, but it shouldn't come first. Jesus should and I don't think your wife knows very much about Him. Again, I'm sorry.