So I hit a huge pot hole which cause a huge boom. Then the passenger rear just sunk and I started hearing a scraping sound. I get out and the rear control arm is resting on the bottom of the inside wheel. So I know my passenger rear ball joint broke... judging by the rear tire turned making it look like I have 4-wheel steering I broke a tie-rod end. Anything else? possible the sway bar end link broke also? Just trying to run through what I'll need tomorrow...

Parts count (so far):
ball joint
tie-rod end

thinking about what holds that wheel in place...I don't think you broke a tie rod, I think your tie rod is what was holding it in place...had you broken the tie rod, the tire would have wandered out from under the car altogether and probably would have ripped a good chunk out of the rear strut tower.

so I imagine you should still replace the tie rod, but more likely than you having broken the ball joint, you PROBABLY ripped it right out of the control arm...this is more likely the case if you live in a salt state. in this case, you need a replacement control arm...and a new ball joint as well.

Looking under the car I can see the ball joint in the control arm but it looks like it is sheered off with no threds on it. This was all done doing ~10 mph so I was basically pulled over when I started hearing the scraping. after turning to wheel to get it in the driveway I got out to notice the wheel turned.

Is the rear setup a 'tie-rod style' or a lateral arm like on a '97+ Grand Prix? Basically am I going to be ordering a tie-rod end or a whole lateral arm?

my bet is you will need a control arm. I have seen this happen twice personnally (my 1994 SLE and my friends 1995 SLE), as well as having heard from other members here in the past with the problem.
Mine happened as I pulled out of a parking lot with two people in the back seat and my right rear wheel come off the curbing at about 10 mph also.

The ball joint is 'fixed' to the control arm? and bolted to the spindle? right? So if the ball joint is still attached to control arm I just broke that? I'm just not getting why you guys say control arm?

Well got it on the road today... Like I thought - I just broke the ball joint. I replaced the other side also just for PMI reasons - it looks really corroded. The tie-rod end was actually fine - tomorrow I'll take it for a alignment.