Lea Michele was a ''nightmare'' to work with, according to a former co-star.

Actor Gerard Canonico, 30 - who was an understudy in the original Broadway cast of 'Spring Awakening' starring Lea and Jonathan Groff - blasted Lea, 33, for treating him and others like they ''didn't belong''.

He commented on Lea's Instagram: ''You were nothing but a nightmare to me and fellow understudy cast members. You made us feel like we didn't belong there.

''I tried for years to be nice to you to no avail. Maybe actually apologise instead of placing the blame on how others 'perceive' you.''

Gerard's comments came after Lea issued an apology to former workmates following 'Glee' co-star Samantha Marie Ware's revelation that Lea had ''tormented'' her for years.

Samantha, 28, tweeted: ''LMAO REMEMBER WHEN YOU MADE MY FIRST TELEVISON GIG A LIVING HELL?!?! CAUSE ILL NEVER FORGET. I BELIEVE YOU TOLD EVERYONE THAT IF TOU HAD THE OPPORTUNITY YOU WOULD '''S**T IN MY WIG!' AMONGST OTHER TRAUMATIC MICROAGRESSIONS THAT MADE ME QUESTION A CAREER IN HOLLYWOOD... (sic).''

While Lea did not refer to Samantha or any other co-stars by name, she said she was sorry for how her actions were ''perceived''.

Lea wrote on Instagram: ''While I don't remember ever making this specific statement and I have never judged others by their background or colour of their skin, that's not really the point.

''What matters is that I clearly acted in ways which hurt other people.

''Whether it was my privileged position and perspective that caused me to be perceived as insensitive or inappropriate at times or whether it was just my immaturity and me just being unnecessarily difficult, I apologise for my behaviour and for any pain which I have caused.

''We all can grow and change and I have definitely used these past several months to reflect on my own shortcomings.''

Samantha did not directly reply to Lea's apology but wrote on Twitter: ''Perceived? Purcieved? Purse? Open your purse?????????????? (sic)'', and she shared a link to a GoFundMe for the family of James Scurlock, a 22-year-old black man who was shot and killed in Omaha while protesting.

Meanwhile, other stars have come forward to expose Lea, with 'Real Housewives of New York' star Aviva Drescher commenting: ''You were once very unkind to me so I am not surprised by your behaviour. You shouldn't judge others before looking in the mirror.''

Actress Emma Hunton - who also starred in 'Spring Awakening' - added: ''This isn't an apology.''

And 'Glee' star Heather Morris tweeted: ''Let me be very clear, Hate is a disease in America that we are trying to cure, so I would never wish for hate to be spread to anyone else.

''With that said, was she unpleasant to work with? Very much so; for Lea to treat others with the disrespect that she did for as long as she did, I believe she SHOULD be called out.

''And yet, it's also on us because to allow it to go on for so long without speaking out is something else we're learning along with the rest of society

''But, at the current moment it's implied that she is a racist and although I cannot comment on her beliefs, I think we're assuming, and you know what happens when we all assume... (sic).''