Sorry I haven't posted in a while, me and my wife have actually been talking a lot lately. As it turns out she talked to our friend about what happened. The friend was as pissed off and upset about it as my wife was. I had apparently misjudged their friendship a great deal.
I talked to our friend today, and she basically told me that she is glad to have me as a friend, but my feelings for her could never be returned. She wasn't mad about it though, she was quite compassionate and understanding towards me. She said that she knows that I cant help the way i feel. I told her that I hope the three of us can go back to being friends again, and she said she would like that. I loved her as a friend first, and now that I have some measure of closure on it I know that those feelings can go back to the way they were.
My wife and I have been really open with each other and have achieved a level of honesty we've never had before. We've always been honest with each other, but she was able to finally tell me something she had kept inside for years. It wasn't anything related to the original matter, but it gave her the courage to say it. If nothing else, some good has come out of this for us.
I have decided that even though I am inclined for the poly lifestyle, I can be perfectly happy with my wife in our monogomous marriage. She has decided that she can't live that kind of way, and I don't want to be without her.
She has also been more open to learning about polyamory. She's still not comfortable with the idea of trying it out, but she's growing more comfortable with understanding the way I feel. She even asked if she could read this thread (which I let her, of course). All in all, I'm feeling pretty good about us right now.