Right. The shard in Harry was destroyed.
So the thing under the chair at King's Cross was
what was left of the last part of Voldemort's soul.

July 30 interview
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Jon: Since voldemort was afraid of death, did he choose to be a ghost? If so, where does he haunt or is this not possible due to his horcruxes?

J.K. Rowling: No, he is not a ghost. He is forced to exist in the stunted form we witnessed in King's Cross.

Does that mean for eternity? And where? In that limbo place?