"The floor of hell is paved with the skulls of bishops.” - St. Athanasius
 
“The road to hell is paved with the skulls of bishops.” - Saint John Eudes

St. John Chrysostom, Patriarch of Constantinople, Doctor of the Church:

I do not speak rashly, but as I feel and think, I do not think that many priests are saved but that those that perish are far more numerous. The reason is that the office requires a great soul. For there are many things to make a priest swerve from rectitude, and he requires great vigilance on every side. Do you not perceive how many qualities a bishop must have that he may be apt to teach; patient towards the wicked, firm and faithful in teaching the Word? How many difficulties herein.
Moreover the loss of others is imputed to him. I need say no more. If but one dies without baptism, does it not entirely endanger his salvation? For the loss of one soul is so great an evil as no man can understand. If the salvation of one soul is of such importance that, for its sake, the Son of God became man and suffered so much, think of the penalty the loss of one soul will entail. (Third Homily, Acts of the Apostles)

Notice all the tonsured monks in hell.

St. John Chrysostom, Patriarch of Constantinople, Doctor of the Church:

I do not speak rashly, but as I feel and think, I do not think that many priests are saved but that those that perish are far more numerous. The reason is that the office requires a great soul. For there are many things to make a priest swerve from rectitude, and he requires great vigilance on every side. Do you not perceive how many qualities a bishop must have that he may be apt to teach; patient towards the wicked, firm and faithful in teaching the Word? How many difficulties herein.
Moreover the loss of others is imputed to him. I need say no more. If but one dies without baptism, does it not entirely endanger his salvation? For the loss of one soul is so great an evil as no man can understand. If the salvation of one soul is of such importance that, for its sake, the Son of God became man and suffered so much, think of the penalty the loss of one soul will entail. (Third Homily, Acts of the Apostles)

Which is why we should pray for our priests.

Not to lessen in any way the severity of the punishment for sins of the flesh, even the unnatural ones, but lest we forget -- it is of traditional Catholic teaching that sins of the intellect are even more evil and deserving of an even greater degree of punishment.

Exactly. Sins of the intellect include schism and heres, which can lead others to a loss of salvation. Thus, schism and heresy are considered worse than adultery and murder for they lead to eternal damnation. Fear not those who can harm the body, but those who can harm the soul.