My Cats Are Driving Me CRAZY! Advise welcomed!

On Wednesday night, I accidentally stepped on one of my cats, Simon, tail. He hissed at me, and then my other cat, Paulie, hissed at Simon. They hissed for a few minutes and jumped around the house and on tip of each other and went crazy and scared each other. I have been separating them like an someone suggested from Wednesday night to Sunday, but now I am letting them see each other with supervision.  They have stare downs and hiss a lot. They both have been fixed and have gotten along great for 5 years. Anyone have any ideas?

They should be getting along better by now, is it slowly getting better? Hissing is all right, they just shouldn't attack each other. What happened was redirected aggression, one got scared at something and took it out on the other cat instead of what scared him. They will slowly start to trust each other again, give them treats close to each other to give them 'good feelings' All the luck!

They are getting better and it is mostly hissing. Thanks !