Why is my x-friend mad at me for nothing?

My friend just suddenly exploded at me for no reason the other day, telling me I flirt with her boyfriend and have a poor personality. I didn't say anything back to her until I denied everything she said. I absolutely, positively, have never flirted with her boyfriend. She tried to apologize, but told me she had meant everything. And then she started blaming her actions on different things, like her Grandpa being sick. Next, she bombarded me with party invitations to "make up for it". I'm sick and tired of what she is doing, so I didn't go to the party. What do I do next?