Frederick Savage, 64, repeatedly abused a girl and boy while living in Halifax.
Savage vanished from Calderdale after splitting up with a partner and was not heard of again.
But his male victim, now aged 30, made contact through Facebook in late 2010.
His first message got no reply. But the victim – abused at the age of eight – saw Savage online on the site’s chat facility.
He sent Savage a message telling him of the heartache and pain he had caused.
Savage, by then living in West Sussex, replied – and later confessed to his wife. She called police.
Savage was jailed for three and a half years at Bradford Crown Court.
The court was told he abused the girl, now 32, from the age of four until she was nine.
Both she and the boy were made to perform sex acts with Savage. He admitted two counts of gross indecency with children, two of indecent assault on a male and one of indecent assault on a female.
Judge Jonathan Rose said: “These were depraved and wicked offences.”
Sophie Drake, prosecuting, said although the female recalled several assaults, the boy could only detail one fully.
“But he feels he was abused on more than once,” said Miss Drake.
The court heard that after Savage confessed, police arrived at his home to find a suicide note.
But Savage, still alive, was taken into custody and interviewed.
The court was read a pre-sentence report from a probation officer. in which Savage cruelly claimed the children had instigated the offences.
The probation officer believed he still posed a serious threat to children.
Savage’s barrister, Michelle Stuart-Lofthouse said his client did accept responsibility for his actions later in the report.
He rejected Savage’s allegation that the children had instigated sexual contact.
She said he was in poor health and had shown remorse.
The court was told he had no previous convictions.
Savage was given credit for pleading guilty to the charges involving the girl, but was criticised for making the male victim take to the witness stand to recount his ordeal.
The judge told him: “These were depraved and wicked offences against defenceless children.
“Your male victim suffered for many years because of what you did to him and as a result his marriage came to and end.”
The judge told Savage had he committed the offences after 2003 – when new sentencing guidelines came into effect – he would have been facing an indeterminate sentence.
He added: “There’s no reason for any person to act in this way to a child.
“I am entirely sure you did so only for your sexual gratification. There’s no excuse, no explanation or justification for such abhorrent behaviour”.
Savage was given 21 months for the three charges against his female victim and another 21 months to run consecutively against his male victim.
A lifetime sexual offences prevention order was put in place.
The court also heard that in 2005 Savage and his wife had been carers for a local authority and had looked after two teenagers.
The judge said: “The suggestion that you could ever be put in a position of responsibility of young children is one I find quite worrying.
“But the sexual offences prevention order should ensure that does not happen again.”