Ok I did some calcs:
Lets say I have a tight 3b range of 6.6%: ((AA:xx,KK$ds,KK$N$N:[Kx+]x,KKxx[43+],[53+]),$0g:xxy,$1g$ds,8764+:xxy,T976+:xxy,JT96+$ds,789+:Axx,AK$N:AxxKyy,AQ$N$N:AxxQyy,KQ$N$N:KxxQyy,15%:RROO$ds)$nt)
(I am probably even tighter actually, but its close I guess.)
Then lets assume I will take the bet-bet-bet line with
a) all flushes and all nut-flush-blockers
b) 9-or-higher flushes and all nut-flush-blockers
c) 9-or-higher flushes and 75% of nut-flush-blockers
d) all flushes and 75% of nut-flush-blockers
Then I will be bluffing:
a) 27% of the time. => He has about breakeven call/fold situation on the river in this scenario.
b) 34% of the time => slightly but definitely profitable call.
c) 28% of the time => very very slightly +ev call.
d) 21% of the time => slightly but definitely -ev call
Well I guess it wasnt that bad at all from him then
Probably should have had a bit smaller betsizing on flop and turn. Or go for the 3-barells only when bit deeper.