Betrayal from a friend?

I worked in a company for many years. When I left I was betrayed by an ociate. That was to be expected because that person had that type of personality. But the part that really hurt me was that another employee also stopped talking to me and I had really thought we were friends. I imagine the reason was the osiate filled that person's head with lies about me, especially since I only ever spoke fondly of that person. I have been so devastated for 2 weeks. I am usually very upbeat and I try my hardest to be kind to everyone and help anyone in need. I find myself now doubting and mistrusting everyone else close to me including my own spouse because of this experience. I don't want to feel that the world is not capable of trusting but I can't help it. Has anyone ever gone through this before. If so, how did you get over it and how long did it take? Thanks for helping.