I am still in shock!!!

Congrats! Even players we're supposed to lose to go chess blind sometimes. You saw it and took advantage!
I, having been a 1500 myself, can tell you that a player of that level has a higher rating than someone with a rating in the 1100s not necessarily because his blunders are less disastrous than those of an 1100, but only because they are a little less common. When I was rated around 1500-1600, I was in Round 3 of the 1st Chess.com Tournament (1001-1400), and I blundered in two winning positions (one of which was totally winning, and the other of which was very advantageous but not a technical win). No big loss of material or anything, just simple mates-in-1 like the blunder that your opponent made (if you look at my games against the lowe - players in Group 7 of the tournament I just mentioned, you will see what I'm talking about).
In other words, if you can avoid making blunders that big yourself, you will find yourself beating 1400s and 1500s before very long.