The England rugby union star, 32, shared an emotional 18-minute Instagram video in which he revealed his own battle with depression. Mr Cipriani said hat former Love Island host Caroline, 40, tried to call and text him hours before she was found dead at her home in east London on February 15.
He said: “She texted me on Friday [saying] she had to plead guilty.”
But Gloucester fly-half Danny, who briefly dated Caroline last year, said he was not able to respond because he was playing in a match.
The sports star told his 211,000 followers he would be sharing voice messages Miss Flack left him a week before her death because “people need to hear it”.
The sports star said: “I have written her messages she is not going to read…But I have had to voice things to her.
“And I am going to play the message at some point, the voice note she left about 15 days ago, because people need to hear it.
“But right now this is me. You can make jokes. I don’t care because it is not going to affect me. She has given me that.
“Because she has given me that I am sharing it with you.”
Mr Cipriani said that opening up to Miss Flack made him feel safe and her suicide prompted him to share his struggle with “severe depression”.
He revealed that aged 22 he tried to buy a gun to end his life and “it was ultimately embarrassment and shame” that killed Miss Flack.
Urging fans to be kind and gentle to one another, Mr Cipriani said: “Embarrassment and shame is not something that should make you do this.
“It’s how we treat people and look after everyone because everyone has embarrassment and shame to some sort of degree.”
TV presenter Chloe Madeley, 32, later tweeted in praise of Mr Cipriani’s “brave” video.
Miss Flack, accused of assaulting her boyfriend, the former tennis player Lewis Burton, in December, pleaded not guilty at a court hearing on December 23.
She was on bail pending a trial that was due to commence on March 4.
● Anyone feeling distressed or suicidal In the UK, please contact the Samaritans on 116 123.
In the US, the National Suicide Prevention Hotline is on 1-800-273-8255.
In Australia, the crisis support service Lifeline is on 13 11 14 or 13 HELP.
Calls are free and will not appear on your phone bill.
Other international helplines can be found at www.befrienders.org.