In the episode where House gets shot, what was the real reason he was shot?

It turns out he was hallucinating the whole episode, so all the reasons we’ve seen aren’t true?

In house’s hallucination, the shooter was a former patient and was cured? Something like that. But House told his wife that the patient was cheating on her and she committed suicide - and that patient blames House for her death.

So what was the real reason House was shot?