[Remco]

I seriously think that I killed the cat by driving too long with the misfire.

You may have but you don't want to just swap parts. That gets expensive.

Get a non-contact thermometer (one of them things with a laser pointer attached) and measure the temperature going into the CAT and out of the CAT. You'll want to get onto the pipe, not in the heat shield.
The outlet should be significantly hotter than the inlet (by easily 100 degrees).
If it isn't, that CAT lost its ninth life.

 

[Remco]

Yes, I agree, and actually a good excuse to buy a new tool, lol. Since it was an aftermarket cat and I ran it very rich for awhile, I will not be surprised in the least if it's cooked.

Yeah, that's me too. I need very little excuse to buy a new toy.. um.. tool.

If it is a bad CAT you may notice the car bogging down at some point, not wanting to get out of its own way. I'd fix it now, while the outside temperature is still reasonable and you don't have to lay under the car on a cold cement floor.