For me personally, there is no place for hypocrisy in my life. I had more than my fair share of hypocrisy when I was in primary school (a separate story for a separate day), which is why I decided that I’m done as far as unauthenticity and shadiness of character are concerned. Whenever I meet someone whom I feel is unauthentic, I would cut the person from my life because I have no wish to deal with misgivings, distrust, disloyalty, etc.
So I cut this person away. It was depressing enough to be backstabbed by someone whom I thought was a trusted comrade, much less learn about the depressing opinions this person had been harboring against me. I felt like I had been totally wrong in my judgment and the friendship was never what I thought it was; it was just an illusion in my mind. I felt I was infected by a virus in my soul and I needed to cut it away, pronto.
If you have been backstabbed by a “friend”, evaluate (a) how important the friendship is to you and (b) whether the offending act is forgivable or not. If it’s a highly important friendship and if the offending act is something you can overlook, then air the grievance to that friend, trash things out, and give the friendship another go. If the friendship isn’t of much weight to you and the offending act is not something you can overlook, then perhaps cutting the person away is the best course of action.