Not 26.Rde1 Nxd3+!

After 26.Kb1, Nxd3 still looks good, but it would be a mistake: 26.Kb1 Nxd3? 27.Qg2+ Kh8 28.Rxd3.

you did a nice job preventing the trap but I think he made a huge mistake here. He should have knight to d3. If I were him I wouldn't worry about the open g file. There's enough defense there to protect a rook attack. If he had moved knight to d3...and followed it up with rook to b7...I think he would've won. He could've had 3 ways of attacking b3 and you would never want to capture his knight on d3 because it would lead to checkmate. And he could've advanced his e file knight up to add some attack as well. I think he got too worried about the open g file and didn't use this moment to keep you one move behind as he attacked.

Reason why I cant do knight on d3: I do 26..Nxg3 27.Qg2+ and taking my knight with rook.

Correct: I had overlooked that when I first thought about the position. The game seems to be coming down to timing, and who has the initiative. This can hinge on just one move. Has Black time to make this defensive move? Or is it a case of necessity? The game is difficult to assess here.

It's a usually a good idea to have a good plan this late in the game. Harassing is good if it's tied into a long term strategy.

Black is still doing OK here...

Black is gaining time after white's time wasting in the last few moves.

This rook dancing didn't provide much, but finally he chooses a good square.

Now 31...f4 would have been interesting...

Weakens the light square diagonal aiming at h7. White at once takes advantage of this...

Here I made mistake cause i did not see your nice move with rook on f2.I think now that at this point i had to play 35...Ne2 and after that probably exchange knight for bishop with Nc3+

That f3-pawn has become a very powerful string to Black's bow - possibly more significant than the pressure against b2. Maybe Black could have retained the initiative by flinging both rooks behnd the f-pawn, viz. 35...Rbf8.

(!) Good catch!

After this I lost my attack and game almost lost 

The Black Q having returned whence it came, White might have considered 37.Rff1, had he been prepared to take the draw! But then Black might have come up with 37...Rbf8!?

Unnecessary - but might be useful as a waiting move. Immediately 39.Bxf3 is risky, but see anon...

Too slow! White must find strong moves to take the initiative.

(?) The losing mistake. Black could have continued exchanges until a "pure" Q+P ending was reached. Though a pawn ahead, White would have found the win extremely difficult to achieve. But it turns out Black could have done much better! It turns out White's 40th was a mistake, but the reason isn't easy to spot. With the surprising 40...Qc7!! Black beefs up the defence against h7, and White finds that his bishop is pinned. Now Black threatens 41...Rf5+ 42.Qg4 Qf7 winning a piece. How would White have responded to the Q move, then? Unable to find a defence, I think he might have had to reconcile himself to the loss of a piece, and, likely enough, the game! Having said that, 40...Qc7 is not the sort of move that leaps to the eye, is it? I'm pretty sure I would have played 40...Nxf3 and hoped for a draw. But it does show that in a real sense Black came within one move of winning the game.