Read the gospel story of Lazarus the Beggar and Dives. After death is a little late. That is revealed to us. I would prefer to give a gospel story precedence over someone like Father Ambrose who has a "distaste" for never being able to say he's sorry...after he's already in the soup!!...so to speak.
Sorry! Christ speaks of the sin which may not be forgiven after death, which we take as meaning that other sins may. Your own Catechism of the Catholic Church speaks of sins being forgiven after death.
All sins, even the worst, apart from the sin against the Holy Spirit, may be forgiven after death. This is the teaching of sacred Scripture.
The history of Judas Maccabeus is an important one in this matter. It proves that the West is wrong when it believes that grave sin, mortal sin, cannot be forgiven after death. The text of Maccabees demonstrates that it can.
To give some context to the incident in Maccabees... What had happened was that many of the dead Jewish soldiers were found to have small idols in their clothing. They had been worshipping idols, seeking their protection in warfare, and the text says that this idolatry is the reason God allowed them to be slain in battle.
So the surviving soldiers began to offer profound prayers that this dreadful sin would be forgiven and Judas Maccabeus decided to send a large quantity of silver to the Jerusalem temple for prayers for the forgiveness of these idolaters.
The whole incident substantiates not just prayers for the dead but the Orthodox hope and belief that sin, very serious sin (mortal sin if you will), may be forgiven by God after death.
This remains the tradition among the Orthodox.
2 Macc 12: 39-46
King James Versionhttp://etext.virginia.edu/toc/modeng/public/Kjv2Mac.html
And upon the day following, as the use had been, Judas and his company came to take up the bodies of them that were slain, and to bury them with their kinsmen in their fathers' graves. Now under the coats of every one that was slain they found things consecrated to the idols of the Jamnites, which is forbidden the Jews by the law. Then every man saw that this was the cause wherefore they were slain. All men therefore praising the Lord, the righteous Judge, who had opened the things that were hid, Betook themselves unto prayer, and besought him that the sin committed might wholly be put out of remembrance. Besides, that noble Judas exhorted the people to keep themselves from sin, forsomuch as they saw before their eyes the things that came to pass for the sins of those that were slain. And when he had made a gathering throughout the company to the sum of two thousand drachms of silver, he sent it to Jerusalem to offer a sin offering, doing therein very well and honestly, in that he was mindful of the resurrection: For if he had not hoped that they that were slain should have risen again, it had been superfluous and vain to pray for the dead. And also in that he perceived that there was great favour laid up for those that died godly, it was an holy and good thought. Whereupon he made a reconciliation for the dead, that they might be delivered from sin.