never encountered this kind of endgame

instead of 41 Kf4, i think Be8 wins

Very interesting (and thematic!).

Your opponent had several opportunities to gain the advantage (26... Bd7; 27... f6 looks promising; also 28... Rxb1 29 Kxb1 f6).  And he never should've traded rooks, but should've played 35... Rb3.

Having said this though, is that bishop ending a win?  I suspect that it is somehow or other, although I'm not able to come up with the method myself!  Certainly Black's 40th move should lose, and not just due to Pawnmower's move, but your continuation also will work, as after 41... Bc6 Black comes up one move short.

Which is why he should've played 40... Bc6.  Now if you exchange bishops both sides queen at the same time.  So you play 41 Bc2 (with the Bxg6 idea latent) and he plays 41... Kd8.  Now he can play Be8, if your king walks to the queenside, or play his king over to meet yours if you head to the kingside.

40 bc6 would've been a true race to the finish line, if i traded bishops he might have had a slight slight edge. The way it played out he stood no chance once i weaseled my king into his back ranks, I see how pawnmowers move would have expedited things but i play cautiously and i was very excited about the win. thanks for taking a peek at the game.