Jealous co-stars ruined her career
Looking back, it is clear as day that those Glee co-stars that tried to paint her as a terrible person were just jealous of her for being better and more popular than them, and so they decided to paint her as this terrible person in order to ruin her career.
A shame that they managed to succeed because Lea Michelle was set to become a massive Hollywood starlet. At least she is now doing something she enjoys in the stage, and her reputation wasn't damaged to prevent her from working in that field.
I guess it is some sort of karma that those co-starts that demonized her didn't amount to much career-wise after Glee.