Scottish Labour leader Kezia Dugdale made the plea as she read the Holyrood chamber a letter from a woman who would have been affected by the controversial clause.
The policy, which limits tax credits to two children with an exemption for women who have conceived as a result of rape, was introduced in April as part of wider welfare reforms.
Defending the move, Scottish Conservative leader Ruth Davidson warned against “wilful” misrepresentation of the process for claiming an exemption which she said could cause “fear and alarm”.
Speaking in a debate on the issue brought by First Minister Nicola Sturgeon, Ms Dugdale branded the policy “utterly horrific and abhorrent”.
MSPs listened in silence as Ms Dugdale read the woman’s account of her ordeal after she was raped by a friend four years ago and went on to have the baby.
The letter said: “I claimed tax credits from birth to eleven months old; the hand-up I needed when I was at my most vulnerable to allow me to re-stabilise my family.
“Tax credits kept our heads above water, a buffer between us and the food bank, for that I am eternally grateful.
“There is no way I could complete that awful form of shame, no matter what the consequences.
“Looking back, that really could have been the thing that tipped me completely over the edge; the difference between surviving to tell the tale and not.”
Ms Dugdale said: “This heart-breaking letter from a rape victim exposes the reality of the Tory rape clause. Or the ‘awful form of shame’, as she puts it.
“That is the burden this Tory government wants to put on victims of rape because it doesn’t want to pay for more than two children in a poor family. It is an absolutely sickening state of affairs.
“It’s not the author of that letter, or any other rape victim, who should feel shame. It is those on the Tory benches here and in Westminster who refuse to act who should feel shame.”
She added: “There is nothing brave about tank-driving Ruth Davidson when she fails to tackle her own government on this appalling issue and hides behind a spokesperson for days.
“I urge every single Tory MSP to stop and think about the ordeal you are asking women to go through. Oppose this clause and finally do some good.”
Ms Sturgeon’s motion to Holyrood said the Scottish Parliament was “fundamentally opposed” to the measure and called on the UK Government to “urgently change its position and remove the two-child cap and therefore scrap the ‘rape clause’”.
Opening the debate, the First Minister said: “The Equality and Human Rights Commission said just at the end of last week that because of this policy there is a clear risk of the re-traumatisation of rape survivors.
“No woman anywhere should have to prove that she has been raped in order to get tax credits for her child.
“I actually can’t believe that in 2017 I am having to stand up in the Scottish Parliament and make that argument.
“This policy isn’t just immoral, although it definitely is, it is also unworkable in practice.”
Ms Sturgeon also pre-empted calls from the Tories for the Scottish Government to use its devolved powers over welfare to act.
“According to the Tories, instead of arguing for the repeal of policies like the rape clause on grounds of common humanity, the Scottish Government should just apply some sticking plaster,” she said.
“If we accept that argument there would be nothing to stop the Tories deciding to no longer pay any benefits for people in Scotland, pocket the savings and look to the Scottish Government to step in.
“It is a ridiculous and unsustainable argument.”
Green MSP Alison Johnstone said: “Surely if you get to the stage where you are asking women to prove that the child they are claiming on behalf of is a result of rape, a single brutal attack perhaps, or conceived during an ongoing abusive coercive controlling relationship, surely you would come to the conclusion that the implications of your legislation, of the impact on the wellbeing, the privacy, of women and children are completely unacceptable.”
She added: “Ruth Davidson asks what a Scottish Parliament is for. It is not simply to mitigate the policies of the Conservatives at Westminster.”
During the heated debate, in which she refused to take interventions, Ms Davidson said she agreed with the two-child cap and the exemptions which go along with it.
“There may be many who disagree with capping child tax credits at the first two children, but not surely with such exemptions to the cap being put in place,” she said.
“So, the question then comes to implementation, and I am sorry to say that on this issue too many people have simply not been clear with the facts.
“I have heard members of this chamber say on television that women must complete an eight-page form in order to receive this exemption. This is simply not correct.”
She added: “It is important that we are not wilfully misrepresenting the process here, causing fear and alarm.”
Turning to the Scottish Government’s powers, Ms Davidson said: “If there is something that some in this chamber feel is abhorrent or repellent, then surely those words lose all meaning unless there is something behind it.
“I don’t want to believe that any member would wilfully misrepresent the process, causing fear and alarm, however I do believe that there are many members of other parties who would wish away tax credits being restricted to the first two children and I would point them to the legislative powers of this Parliament.”
She added: “If she (Nicola Sturgeon) chooses strong words but chooses not to act, that would indeed be shameful.”