Poor fold on my part?

[MastiffPaul]

I would have pushed A2o into his raise.

I also would have raised your K9o UTG, enough to cover the short stack.

Villain is correct to raise many hands here. Your hand selection should be much wider than it should be when you are, say, 10-handed, because you are more likely to have the best hand at the table with something like K9o. Don't be afraid to be aggressive, especially when you have your opponents covered while already ITM.