How do I deal with a two-faced mom trying to sabotage my reputation?

I am an older mom who enjoys helping out at my children's school and was always well-liked. Then I became friendly with a younger mom who, unfortunately, is my neighbor. This woman is very connected and very involved with PTA. She has suddenly become very distant and coincidentally other moms in the neighborhood and even a teacher friend are avoiding me, not answering phone calls, emails, etc. I had a feeling this woman was talking behind my back and my suspicions were confirmed by a neighbor. I have been been a good friend to this person, have been there for her when she needed a shoulder, not to mention have given her hundreds of dollars worth of toys, furniture, and clothes over the years. I consider her to be toxic at this point and really don't care to be her friend, but how do I restore my reputation with my neighbors and school friends? I should note that I confided in this mom when I thought she was my friend. I shared with her some very personal information about my past and I have a hunch she has divulged this to others. I should also mention she has a negative disposition in general and is very critical of others, but she has a way of seeming so innocent. To top it off, she is a Born Again Christian and very active in her church!