therealdjlaura

For me it depends on the player. In other words, if I know someone is 3-bet bluffing too frequently (always 3-betting light) I'll gladly shove with TT or better.

I don't study solvers or GTO in depth right now. However, I think you need to keep the pressure on him on the turn. I would have bet at least 75% pot on the turn. Maybe even over bet the pot a bit. If he calls the turn bet you know that 4 on the river could be trouble. Or, at least, you know you may be in some kind of trouble. You can check, fold river if you need to and save some money. I personally would have folded, but I play pretty tight. Still, higher 2-pairs, sets, and the straight all have you beat. Unless he's over bluffing and super aggro, this definitely smells like trouble.

I would have bet about 30% of the pot on the flop. No way would I fold to his river raise. Sure he could have a bigger flush, but there are so many more hands you beat. He could have rivered the straight. He may just be betting an ace. He could even have a lower flush. You played the hand weak by checking down so it's also easy for him to just bluff that river. He probably would never think you even had a flush draw.

Don't slow play when you smash a flop. Play your solid hands fast and STRONG. Play less in early position, and 3 or 4 bet from late positions with your premium hands. Make sure your bet sizing is large enough both pre and post flop.

If you have not been through the NLH "From the Ground Up" course with Pete Clarke, I HIGHLY recommend it. I have gone through it twice and occasionally go back to certain parts. After that, I purchased the Foundations course with Phil. My online low stakes game has improved tremendously after taking the time to seriously digest the material in both courses.