9. ... f5 looks like a crappy move to me. You just have to arrange to kick the knight while its still convenient to do so, so 10. ne5 looks common sense to me.
OTB positional game I lost - some tips pls?

um, you out rank me, however, to answer one of your questions, If you feel yourself getting crushed, yes, looking at their side is good to see their plans, and also just walk away, get water, and move around.

Thank you guys for all this advice, it is useful for me Looking forward for some other reactions, if any arise
I thought excellent instincts in your notes. Trading off your DSB probably wasn't best as it weakens e5 which in turn can weaken the whole diagonal. Also always keeping an eye out for trading the LSB in the endgame is probably a good idea. Though the engines might say up the exchange is equal to the two bishops, together they cover a lot of squares and the rooks have a hard time getting active. Here against mate threats and extra pawns, a brutal example of the power of 2 B's on an open board.
Related to the e4 N post. With the option of the kick with f3, there could be a couple of choices. The first is the piece kick like you did but, unless forced, you want to have a plan to try to take advantage of the hole left behind after the piece moves before you implement. Equally good might be getting some of advantage from where the kicked piece lands.
Another idea is exchanging the posted piece then challenging the capturing pawn immediately with f3 so either the opponent's pawn falls by advancing or you get some benefit from it's exchange on f3.
I'm not saying that there was something better than your kick in the game. I didn't look that closely, so I don't know. These are just a couple of general ideas for dealing with that type of advanced post.
The pawn structure in the opening was like a carlsbad.(Edit: it is not exactly like a Carlsbad as Black’s pawn isn’t committed to e6 making it possible to develop his LSB. Black’s DSB is also fianchettoed)What I like to do in these positions is to get my knight to e4(e5 if you’re White) after developing my kingside and queenside knight. After that your pieces start to find places for themselves.Do not hesitate to recapture on e4 with a pawn as it will cramp the opponent and it’s easy to defend. If White plants a knight on e5 chop it as their pawn on e5 will be doubled. If White starts a minority attack with b4 shut it down with b5.Hope this helps.
P.S this is all my opinion

Thx a lot again for all the ideas, it is nice of you you this suggestions, I am happy I posted this game here, definitely I will learn something about these advanced posts and how to counter them

After his rook sac, his realistic options were:
1)backrank mate
2) skewer your king and rook or skewer your rooks using bishops.
3) push the passed pawn.
You should have traded the rook and bishop. If he tries to avoid the trade, then you can gain the tempo and push his pieces to bad squares.. Then, blockaded or captured that passed pawn, then his game was over.

Ok, I didnt understand the final move of black. Is it not losing for black after that pawn is captured by rook?

No Ashvapathi, Black goes Rd6+ and gets the bishop. What's the deal with this game shown as having been played in 2021?

I am not sure about his last move (I wrote it above - you can check the note number 4), I didn´t write the last one to the list of moves, but the other moves are correct - I will have to ask him about his move list to be sure about his 40. move)...this one 40)...d2+ will make Black worse, that´s true, but anyway I will not be able to exploit it with 2,5 mins on my clock against more experienced player
Of course it was not played 2021 - I missclicked it when choosing date...it was this year 2017, just few days ago. I am sry for this guys
About 5.) h3 - thx for feedback that it is prolly not so good move... I read about such moves are better to be avoided in the opening, but computer is fine with this move and I saw preventive h3 (against possible ...Bg4 pinning the Nf3 even in the games of strong players, even in some Karo Cann positions)...anyway this "passive" move prolly encouraged him to play aggresively, so I will reconsider this in future games
And about similarity with Carlsbad structure...I think it is time for me to play some videos about some common structures/build-ups (like Carlsbad), so I can improve in positional chess, thx!
@Koobek
Your position kind of reminded me of those which can be found in the Dutch Stonewall. Here's some games with a kind of similar posted Knight. I think examining Petrosian's moves might help in facing the situation again.

Thank you very much for these grandmaster´s games shown, I like especially the simple idea that Nf3 can jump to e5 and then the other knight jumps to f3 to give him very strong support.
I tried to implement this idea to my commented game and made this variation with the help of the computer - tactically it seems not possible to plant knights both on e5 and f3 to make mutual support (because Black will most probably want to swap Ne5), but resulting pawn on e5 really seems to cramp Black´s position (as ArtNJ proposed above) and there will emerge a very pretty square for the remaining White knight in the centre - d4! I think I will enjoy playing White´s position here!
Description of the game:
I played this game as White yesterday at the local club (45 mins per game + 30 sec per move after the move 20)
My opponent built a knight outpost on e4 which caused me to think a lot, this type of position was quite new to me...I lost a lot of time, I didn´t think very productively, and when I reached move 20 I had less than 10 mins on my clock and the Black had 25 mins.
Computer analysis shows that White was in fact ok in the opening (I felt a bit worse compared to the reality of the position, because I didn´t see my active chances).
Giving up Bishop pair on move 17. was unnecessary and caused more trouble in fact (I did this move mainly cos I decided for a simple move because I wanted to save some time, eventhough I saw Black squares around my King will be weak)
21. Nc5 ? is a mistake cos it allows Black some tactics - I was a bit lucky here anyway, after 26) Rxc5 according to comp the position is even
The resulting endgame I didn´t play so well, I missed opportunity moving my rook to 7th rank on the move 33) and then the position quickly deteriorated because of the Black passed pawns marching, supported by the bishop pair.
My notes and questions:
1) I realized I was just pondering instead of clearly thinking after 9)...f5 when Black secured the knight on e4. During the next few moves my mindset was similar...feeling a bit uneasy and unsure how to counterplay. I believe resulting position after 9) ...f5 is prolly not so much about tactics but mainly about finding positional counterplay.
How do you approach similar positions? What is the useful plan? Where are Black´s weaknesses after apparently aggressive 9)...f5? What is he giving up when moving the f-pawn? (I think that his e-pawn might be weak, also e5 square, but I was not able to exploit it)
2) What is psychologically good to do if the resulting position is not so pleasant for you? I think prolly it is good just to go away from the board for a short time and to try to see it from the other side ("flip board") - just not to sink into unproductive state of mind...also prolly to think a bit like playing Blitz game can help, not to take everything so seriously and trying to "count" uncountable...
What do you propose?
3) I realize I have weaker play in endgames...if you see an endgame like resulting after 26)...B g3, what is the general White´s plan to hold the draw?
I think it was very useful to exchange lightsquare bishops, but I missed opportunity to do so tactically (when his Bish was quite constricted on a4.)
4) About his last move I am not sure, I forgot to write it to the move list...prolly it was not d2+...but it was some check...I didn´t have much time and felt quite hopeless, so I resigned...but the last move 40)...d2+ is prolly not the proper one
Any ideas about this game are very welcome, thank you in advance!