As soon as I see this flop I'm typically in triple barrel mode. Great equity, low showdown. Bet/bet/bet is good improve or not.
He donk bets river here, and we have to call with straight-combos. Even possibly some stuff like AA/TT, but generally not too much wider without a specific read. He obviously has a lot of flushes, but not only flushes, plus we get some pot-odds.
I doubt you can fold a rivered straight unless you have a pretty cast iron read on him in theory. I like your line and I think I would do the same but actually at my stakes if I look at river pot donks after facing double barrel (i've only got 9 mind you in last 200k hands) it was the nuts 100%. Probably sample size I suppose but at NL10 no-one is pot donking much but a flush here.