The mother-of-two's baby son was stillborn at six months in 2010.
Her Twitter account has now been taken over by a friend to try to stop the abuse.
The trolls accused her of being to blame for the death of her baby and suggested she had mental health issues.
It started when the 31-year-old singer tried to highlight the prejudice shown towards immigrants.
But, when mostly anonymous trolls started abusing her things started to get nasty.
It prompted Lily to reveal that she suffered PTSD after the stillbirth.
