pot-sized mistake?

[piggity]

15/30 B&M.

I raise with A[img]/images/graemlins/heart.gif[/img] A[img]/images/graemlins/diamond.gif[/img] from the CO, unknown BB calls.
Flop is Q[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/spade.gif[/img] 4[img]/images/graemlins/club.gif[/img]. BB checks, I bet, BB calls.
Turn is K[img]/images/graemlins/spade.gif[/img]. BB checks, I bet, BB calls.
River is K[img]/images/graemlins/club.gif[/img]. BB checks, I bet, BB raises...

I out-play myself in my head and fold. Please beat up on me for folding. Thanks.