What does Elizabeth mean when she criticizes Miss Bingley for her judgement of Wickham Chapter 18

Jane has informed Caroline Bingley about Elizabeth's new relationship with Wickham. Caroline warns Elizabeth not to trust Wickham. In fact, she insists that it was Wickham who mistreated Darcy and not the other way around. Elizabeth reacts rudely, rejecting the suggestion. Jane also tells Elizabeth that Bingley believes Wickham to be the villain in the situation, but Elizabeth dismisses this as well. She concludes that Bingley must be blind to the truth because of his friendship with Darcy.