There is still something else that person must face. And that is atonement to God for this sin and expiation.
Atonement has to do with justice.
Here is Trent on Christ's Atonement for sin.
Whence it came to pass, that the Heavenly Father, the Father of mercies and the God of all comfort (2 Corinthians 1, 3), when that blessed fullness of the time was come (Galatians 4:4) sent unto men Jesus Christ, His own Son who had been, both before the Law and during the time of the Law, to many of the holy fathers announced and promised, that He might both redeem the Jews, who were under the Law and that the Gentiles who followed not after justice might attain to justice and that all men might receive the adoption of sons. Him God had proposed as a propitiator, through faith in His blood (Romans 3:25), for our sins, and not for our sins only, but also for those of the whole world (I John ii, 2).
Christ had to ransom us and He did so out of love for us. The work is done. But, we continue to use our free will to choose evil in mortal or venial sin.
For these sins, we must make reparation and atone for ignoring the mercy and justice of God.
We can do sacrifice on earth for our sins. I think St. John Paul II did this in his long life, especially with his suffering at the end of his days. His example is for all of us.
The acceptance of suffering on earth is primarily to atone for our sins, to make reparation.
Reparation is justice given to God for sin. If I get a speeding ticket, I have to pay for breaking the law. If it is a minor offense, it does not go on my driving record, but if it would be a major one, that sin would follow me around, as it were.
So, too, with our forgiven sins.
Reparation and atonement need to be made to an All-Perfect, All-Merciful and All-Just God.
We can ask God for our purgatory on earth, but be prepared for great suffering.
