I agree with joanandboys.Your so called friend probably did have the hots for your Matt. She sounds like a total back stabbing B**** to me. Good riddance! I also think that if Matt's best friend was really that close a friend, he will see the light about this girl soon enough.You can't fix the friendship for him..they'll have to work it out themselves.
Don't let what your ex friend said about you bother you. She was just trying to hurt you so she said the things she knew would hurt the most ie:comparing you to your ex. You Know better than that so don't even listen to the jealous B****.