[Sounded Simple]

I cant think why you didnt raise this up pre-flop.
You almost certainly have the best hand pre-flop but are almost sure to be outflopped multiway - attack those limpers!!!

As played on the river Im thinking he has the flush, many limpers means more chance of sooted cards hanging around.
I really cant think what else he flat calls the flop but min raises the river with.
I check/call a small bet.