"She is fed up with the toxic atmosphere of Broadway and is leaving her show in disgust because of those feelings."
But, aside from everything else, many people might feel that to leave Broadway entirely for a reason like this, rather than sticking around and trying to help make things better. is the least helpful and worst possible choice,
My own personal opinion: Olivo seems to have been unhappy in the theater (or, at least, on Broadway) almost from the start, for whatever reasons, as exemplified by her attitude towards the press during WEST SIDE STORY, the fact that she did actually leave the business for while (and was then apparently was persuaded to return), the fact that she maintained a scattershot performance schedule in MOULIN ROUGE, and so on. So while of course her point about abusive behavior on Broadway is 100 percent valid, I think the reasons for her leaving are a lot more complicated than that.
And now, an important P.S.: From all reports, the way Arthur Laurents treated the cast of WEST SIDE STORY was truly despicable, so perhaps Olivo's subsequent statements and behavior can be attributed in part to a sort of theatrical PTSD.