smallville Season.6 - Episode.12

Clark is attacked by a phantom zoner in the barn; he is experiencing an alternative reality created by the zoner.
In the hallucination: he is held in an asylum, having no power, and is told that all his memories are fabricated by himself to avoid reality after his parents died in the meteor shower; Lana is still in love with him; Lex is a paraplegic; his mother is married to Lionel. To cure his disease, he has to undergo a operation.

But he finally snaps out of it with the help of a mysterious man previously saved him from another phamtom escapee.