Don't know what I am feeling

I am having mixed feelings about something and feel I need to get my thoughts out.

I recently found out that a "friend" of mine whom I thought was a "good friend" really isn't what I thought they were, and in fact are two faced.
Awhile ago while I was having some rather large changes in my life happening I mistakenly thought this person was a friend of mine and as friends do, trusted them with thoughts and feelings pertaining to what was going on and believed them when I was given information or support. Now I have found some pretty strong evidence, an e-mail, to show that they are not the friend that I thought they were and that I don't know who they are.
This e-mail had lies, about me, lies about my family and it makes me wonder what other information they have said is lies to me and to others about me and my family.

I have not spoken to this person because I don't know what to say to them. Or for that matter how I am feeling.

I know that I am angry, anyone would be with this realization about a friend and with what was said.

I know that I am hurt, this is a loss of someone whom I thought was a good friend and that I cared for.

I also know that I am sad, I can not in good conscious continue to be friends with this person knowing what they have said and possibly what they have done.

I always try to be a good friend. I know I have always been a good friend to this person. Helping them when they need to move, being supportive when they were changing jobs or going through a tough time with kids or break-ups, helping any way that I can. Now I know that the friendship was a one way road and apparently they other side is a two faced road.

Should I confront this person? Should I waste my time on them? Or should I just slowly let them get the gist that I am not in the mood for what other lies they are going to say? When I first found out I wanted to take it to them and show them what I found and call them on the lies. After a few days I have come to the conclusion that right now karma has bit them in the butt. I don't know...I just know that I am really going to miss the one side that I knew and trusted. But it's not worth having to worry about what may be said or what may not be said.
I also can not ignore the fact that my family was brought into the lies. That is NOT okay! For now I can mourn the loss of what I thought was a good friend and maybe move on with out having to get to the point of confronting them. It's sad. I am glad that I have so many wonderful friends that I have had for so many wonderful years that count, and that I love wholeheartedly.
To those I say thank you for being my friend. And to the one I say I'm sorry and goodbye.