So, what do you think? Do I pat myself on the back for handling an emergency relatively well? Or do I smack myself across the face for nearly burning down my house through sheer stupidity?
Do both, but smack yourself particularly hard if your wife hasn't already done that.

Only other comment, always have the FD come check it out. Let them know that you knocked it down with the extinguisher but have them come. We carry wonderfull devices call TICs (thermal imaging cameras) that let us tell without having to open up a wall (usually) if there has been any extention that you can't see.
Good job otherwise.