There is a lot to learn form this hand, from a strategic and mental game point of view.  

Strategy specific:

I like the check/call on the flop, although i do see many players simply betting this hand and i don't know how much we should take into account we have the backdoor nut flush draw. The check/call line seems logical as all hands that are draws would call a bet anyway would probably be betting if we check to him - to fold out JJ or worse and maybe some weaker mid pairs by the river. He does have plenty of worse hands that may struggle to improve, mostly low pairs or a hand like he had where he has the bare gut shot draw AJ/AT/T9

i'm a little surprised you feel he would check back Kx on the turn flushing card. As the 3bettor you would often cbet your flush draws. so he might feel obliged to protect his Kx versus your JJ/TT with a club or AQ with a club etc 

i would remove low flushes and high pair or better from his range at this point. of course all of those hands could still be in his range, just from my 'standard' way of playing on turn flushing cards when the 3bettor has checked out of position. as villin, i would still give the 3bettor (hero) some nut flush draws like AcJc or AcTc just that they very unlikely - 2 combos. 

you did analyze the spot correctly during the hand. you felt he was polarised and you had a strong bluff catcher. so you made a great call, now..

From a mental game point of view:

Originally I feel the river is a complete blank but when he bets $10, i feel like I have been punched in the stomach

do any overbets cause you to feel like this? 

also, i know i have made the mistake before by simply not having certain hands in villain's range. i would be playing a hand and have removed parts of their range (often incorrectly). we see he did call a 3bet with ATo which personally i don't do - i feel i play poorly with this hand postflop versus a thinking player in 3bet pots. 

'fuck it' i call - versus aggressive players you are required to make more calls than you used to. this is as you move up to higher stakes you encounter more aggression from good and players alike. This means that you need to begin finding reasons to clal rather than finding reasons to fold on lower stakes. 

Originally I feel the river is a complete blank but when he bets $10, i feel like I have been punched in the stomach

Poker is suppose to be fun man! If this is really the feeling you get when facing bets you might want to focus removing the money element of the game. If you feel like you just got hit in the face with a $10 frozen foot long sub, you're probably doing something wrong BRM-wise or mental game wise.

No

+1 to Hustla

dont really feel like hed check back Kx on the turn, youve kinda turned your hand over as Qx at best, hes really got no reason to fear you have better than him, and hes likely going to bet for protection as you can have some clubs.

My general thought in these spots is that if he wanted to bluff he would have done it on the turn when it was a good card to do so. But his bet really makes no sense from a value perspective unless he thinks its going to induce you to call.  Really its just a leveling game here. We are at the top of our range, his bet is polarized, so I think calling is fine. 

Id make a note of his hand and the situation for future spots.

Stay disciplined , go with ur instincts if ur reasoning makes sense tilt can start bleeding lots of $$