I'm not sure if these quotes describe a purgatory as it is known in Christian theology. Purgatory is the process of purification of souls who haven't quite been good enough to make it directly into heaven but who don't merit hell either.
There's no intent to sanctify here but some form of fearful torment. However, since LotR does not specify what lies beyond the gift of death for Men, it difficult to say this is hell.
Houses of lamentation is a very poetic expression, not something I would have expected from Witchie. maybe he shares some of Saruman's eloquence.
Whatever it is, it sounds worse than road rage.
