First off...how did you get under the car without lifting it up...that's got me perplexed!
Second, of all the things we went over in auto mechanics in HS, the two things I remember most...always be sure the seal comes off with the filter, and never take apart right and left on a drum break job at the same time...leave one assembled for reference. That said, I feel your pain. We've all done something we're not proud of at some point in our lives.
As far as what to do with the car...if you're ready for a replacement car anyway, tradin is your fastest, easiest way out of this mess. Just be sure you wash under the car really well with some engine degreaser, no sense leaving any clues to the appraiser at the dealership as to your dilemma...
