In a soul-bearing interview accompanying a serialisation of her memoirs, Ms Davidson told how her arms and stomach carry the scars from cutting herself with blades and broken glass, and said she still has to manage her mood to avoid a fresh bout of depression.
Her announcement that she will not “ever” seek a parliamentary seat at Westminster will dismay Conservative moderates, who looked to Ms Davidson to salvage their party from the damage and division of Brexit.
“I value my relationship and my mental health too much for it,” Ms Davidson told the Sunday Times, when asked if she could succeed Theresa May, “I will not be a candidate.”
Conservative MSP Adam Tomkins tweeted: “The first time I met Ruth I knew she was special. Over the years we’ve grown close. Still, she amazes and astounds me. She’s awesome, isn’t she.”
The SNP justice secretary Humza Yousaf also praised Ms Davidson, posting on Twitter that “it can only help that folk from all walks of life speak about mental health”.
And the Scottish Labour leader Richard Leonard went on social media to say that her “decision to discuss her own experiences including self-harm will mean a great deal to a great many people”.
Speaking at his party’s conference in Brighton, Scottish Liberal Democrat leader Willie Rennie said: “How Ruth remained so composed and assured whilst being so frank and open about such a troubled chapter in her life is beyond me. She has my respect.
“Mental health affects millions of people from all walks of life. That’s why I have treated it as a top priority and that is why we need to work hard to make it easier for people to get the help they need when they need it.”
The mental health charity SAMH also welcomed the Scottish Tory leader’s openness about her struggles with poor mental health.
In extracts from Ms Davidson’s memoirs, she tells how the suicide of a boy from her home village when she was 17 sent her into a “tailspin”.
A year later she was diagnosed with clinical depression but the medication gave her “desperate, dark, terrible dreams”.
“I started having suicidal thoughts,” she wrote.
Ms Davidson said she became “very good at covering things up… wearing long sleeves in summer and that sort of thing”. She said she is “still frightened” of going back to the “psychological place I once inhabited”.
Although she has not had a significant depressive episode since 2006, she said she turns to “structure, exercise, forward momentum, measurable outcomes” when she is feeling anxious.
The Scottish Tory leader is pregnant with her first child and also cited family as a reason why she was ruling out a bid for 10 Downing Street.
“On a human level, the idea that I would have a child in Edinburgh and then immediately go down to London four days a week and leave it up here is offensive, actually offensive to me,” Ms Davidson said.