|Miley Cyrus & Sinead O'Connor|
The 'Nothing Compares 2 U' hitmaker penned a fourth open letter to the 20-year-old star on Tuesday, hitting out at Miley for calling her "crazy" during an interview with Matt Lauer on the Today Show on Monday, and urging her to be more supportive of people battling mental health issues.
In the lengthy Facebook post, the Irish star wrote: "You've said on Matt Lauer's show (where you again refer to me as 'crazy') that you don't understand why I have been upset with you.
"My problem with you stems from your response to my first letter."
Miley previously compared Sinead, who has bi-polar disorder, to troubled actress Amanda Bynes, who is currently in a mental health clinic, and shared suicidal tweets Sinead posted two years ago before she sought help.
In her latest letter, Sinead also wrote: "I would very much like you please to apologize to myself and Amanda Bynes for having perpetuated abuse of both of us on the grounds that Amanda has had 'mental health issues' and that I experienced suicidal compulsion and was open about seeking help in order to save my life."
She added: "As a result of what you did I have had numerous communications from people urging me to commit suicide.
"Luckily I am a strong person. And I have four children whose lives would be destroyed if I were to buckle under the abuse you set me up for. If I were not, and or I did not have four children, these types of communications and these types of articles and remarks could have had their desired effect."
Sinead also hinted Miley's comments about her are affecting her career.
She said: "I have four children to support. I can't do that if people believe me to be unemployable."
The 46-year-old star claimed she only wrote to the 'Wrecking Ball' hitmaker initially to offer some motherly advice and isn't interested in a "feud".