Why do bret hart and shawn michaels hate eachother?

When Brett Hart moved to a rival faction from the WWF now the WWE he was the heavy weight champion, in his contract it stated that he would never lose in Canada, where he was from and where the Hart family were the first family of Canadian wrestling, Vince McMahon and Brett Hart had a deal that he would win the match against Shawn Micheals in Montreal then he would relinquish the belt, during the match the referee did a fast count and Bret Hart lost to Shawn Micheals, Brett new that Vince McMahon had betrayed him and spat in his face, thus inadvertently creating the A-hole boss persona that McMahon has milked for years. Shawn Micheals swore up and down to Brett Hart that he did not know anything about the double cross when in reality he did. In other words he too stabbed Bret Hart in the back. Sorry if this shatters any illusions that you may have about wrestling matches not being predetermined, and choreographed, but you did ask and it is still some damn fun sports entertainment!