The dancer, who was diagnosed last May, was accused of being a narcissist and attention-seeker.
She was also told she should be hiding away and getting on with it, instead of trying to help others.
And now she is calling for the most extreme trolls to face criminal convictions.
Amy says: "I wish these people realised what they are doing.
"I wish they could see the effect it does have. It's like putting a nail in a piece of wood. You take the nail out and the wood is scarred for ever. It's never the same.
"And making those nasty comments is doing exactly that." Amy was diagnosed with the most aggressive form of breast cancer aged just 32 last May.
When she was diagnosed, she decided to allow cameras into her most personal and vulnerable moments in the hope of reminding women to check their breasts.
"I wouldn't want anyone else to receive the messages I did," she says quietly, ahead of her new documentary, airing on Monday.
"Sometimes I was up at 2am and I couldn't sleep because the steroids were keeping me up.
"I was so low and then receiving those messages was heartbreaking.
I just feel like it's not spoken about."
BULLYING
She adds: "You hear on the news about teenagers taking their lives because of online bullying. I witnessed a bit and I got to understand where people are coming from when they are feeling like that.
"When someone is bullying someone online and they take their own life, it's kind of like manslaughter. Is there going to be punishment to stop people doing it? It's awful." Some messages even mocked Amy for having caught her own cancer relatively early - she was diagnosed at stage two.
"They said I was a narcissist and an attention seeker," she says.
"It was: 'It's not even stage 4.
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