How I converted a simple mistake of the opponent into a checkmate

Hi to all my readers!

Lately I stopped playing games. Zero Rated games. What changes between rated and unrated? The people who play unrated games usually fear of losing. Nothing else. 
I stopped following much of chess and suddenly in the tactics trainer I was touching 1290 and 1300. I was surprised. I thought "It might be because of the occasional top game that I used to watch." I started watching more of those blitz games. Then I drastically started dropping my points. I realised that this was probably because the mistakes that chess players did in the bullet and blitz games that they play.
"Sometimes we fail to see what is right in front of us" Nothing exemplifies this more than these blitz/bullet/rapid chess games.

So I play a few matches and to my satisfaction I manage to produce a good game, ofcourse with the help of my opponent's small silly mistake.

One must know how to convert these opponent's mistakes because sometimes we fail and the game goes in the opposite direction. So here is the game. It was a short one (13 moves) but I felt good because the mistake was converted very well by me and in a very short duration of time.

 Now I hope to get back up on the tactics ratings.

Ciao!