MTT 3 handed, blinds 800/1600 we are in the SB with

~70K
Button has us covered by approx 1k. Button is a "reg" not played against them a whole lot didn't have any solid reads before tonight. They don't fold to 3 bets, and will call jams wider than they should, they most seem solid but have made some weird moves, like raising a continuation bet on Ace 2 2 r/b in a 3 bet pot (button>BB).
BB has 30k. BB is a good solid player.
Button makes it 3325, we 3 bet to 10775, he calls as per usual.
Flop:

(Pot 24750.00)
We bet 11200, call.
Turn:

(47150), we have 46k behind.
Check Check
River

.
Check, they jam and we? Views on all streets pls.