When do you stop an arugument

I try and follow the adage "Stop arguing with fools" . It is just not possible to convince them and just not worth it. There are times when I just get pissed when people get personal and underestimate your knowledge. Angry infact. I declare such people as fools and just stop listening to them ever! My attitude is indeed sad! But heaven forbid I am a recovering short tempered person.
Should I go ahead and prove that I am right? Should I just let the argument rest in peace? Or do I confide in a friend that I am indeed pissed and try and see if that even headed person thinks I am right? God do I need assurance or what?