5. d3 looks a little awkward. I'm leaning toward 5. Bb3 as an alternative.
Your comment on 8. ...Nxd5 confuses me. If you meant "lost a piece" as in getting behind in material, I don't see that until 15. Qd3??. If you meant "lost a piece" as in trading it off, you were still fairly equal after the trade.
18. Re4 isn't good because he can just play 18. ...Rxd3.
I don't know what made your opponent take your rook on move 22, but he did, and you got back into this.
36. Ke1?? lost immediately, and I don't know why you moved away from the pawn. You would still have a lost game after 36. Kc1, but it would have taken longer, giving you chances for a stalemate.
What do you guys think of this game, i'm "colabomb" (white).