She explained she had thought Pleasted was just a nice old man, adding: "He's f****** harmless now, ain't he?"
At the time, Pleasted was on bail awaiting trial at Snaresbrook Crown Court on two charges of sexual assault on two children aged under 13. Police were investigating a further allegation he had abused a third boy.
The Old Bailey heard that Pleasted had a string of convictions for sexually assaulting boys between 1970 and 1991.
The serial child abuser, who also went by the name of Robin Moult, had a total of 24 previous convictions for sexual offences before he met the children he was accused of molesting last year.
He served sentences of between nine months and six years for sex crimes which included indecent assault on a male over 16; indecent assault on a male under 16; indecent assault on a male under 14; and buggery.
But before the fresh allegations emerged, Pleasted had become a well-known community figure running a bric-a-brac stall from a local shop, the court heard.
Sands, believing he was just a nice old man, had befriended him and used to go round to his flat with home-cooked meals.
She sobbed in the witness box as she insisted that she did not mean to hurt Pleasted when she went to his flat armed with a knife on the night of the killing after drinking a bottle of brandy.
She told jurors she had gone there to plead with him to admit his crimes and spare his young accusers from having to go to court.
But when he answered the door, he ignored her request and just "smirked" as he told her the boys were all liars who had ruined his life.
Sands said: "I was frightened. It was not how it was meant to go. He was meant to listen to me."
The jury of 10 women and two men deliberated for three days before clearing her of murder and convicting her of manslaughter by reason of loss of control.
Sentencing was adjourned for reports and will take place on a date to be fixed in September.
Trial Judge Nicholas Cooke QC told the jury that an inquiry was under way in to the decision to bail Pleasted, adding that the jurors were clearly "troubled by the background" of the case.