[jcm4ccc]

I would have folded on the flop. It's such a weak holding; it's possible that you are already beaten. If not, your hand is quite vulnerable to getting beat on the turn or river. There are straight draws and flush draws on the board. Your opponent may also have overcards. So many ways for you to get beaten (if you're not already beaten).

I assume you raised on the flop in order to make your opponent fold. When he didn't (and didn't reraise you all-in), you have to assume he has something.

It's quite possible that the SB was drawing to the flush, and decided to try a bluff on the river when he didn't hit it. However, your hand is too weak to stand up to a bluff. I would definitely fold.