Newbie Question - Analysing Computer Analysis

Hi everybody. This is my first post in the forums, hope I'm not doing anything wrong.

So, I often submit my games to computer analysis, and normally I understand the computer's reasoning. But for this move specially I didn't, so I would like to ask you guys to shed some light!

My varation is not bad at all, I think: if white attempts to escape with the Queen, I win a rook for free. If 18.Qf3 for protecting the rook, then 18... Rxd1 19.Qxd1 Qh1+ 20. Kf2 Qxd1 and I have a queen for free. If 18. Qxg1 (what I was actually expecting) then 18...Rxd1 19.Kf2 Qh1 and both queens are in game but I'm 2 points ahead thanks to the rook in d1. I didn't see any great play for white in this position, everything would lead to a loss.

Apparentely the computer disagrees. The computer analysis variation seems great to me thanks to 18.Qxe4, but... why not 18.Kf3 instead, attacking both my queen and my knight?  I honestly missed the point in this move.

is it Rad8 you reffering to?

well 17.Qxd8 Rxd8 18.Rxd8 Qxd8 and then 19.Bxg3 

so you lost your knight in this exchange

No i think he is asking why the computer suggests 18Qxe4 instead of Kf3.

And the answer is because black can now force the queen exchange which results in a better game for black

-> 18.Kf3 Qxd1+ 19.Qxd1 Bxg4+ 20.Kxg4 Nf2+ 21.Kg3  Nxd1

There are some variations like 20.Kxe4 which lead to the same result.

Now the material situation is the same like the proposed varation from the computer analysis but black managed to trade queens which is better for him because he is leading materialwise.

I wouldn't classify that as a loss, since I'm winning the queen. Plus, I could play 19... Qd1+, not only checking, but locking the knight and the rook and calmly work an mate with my light bishop.

you right that whas my mistake

Yeah, that sounds reasonable; in your variation I win 2 pawns, exchange queens and trade a bishop for a rook. In computer analysis its only one rook for a knight, so it makes more sense for the computer to chose this path. Thank you very much.