Horrible Behavior Post-Neuter

Thomas was neutered about two weeks ago and seems to be having a behavorial and aggression relapse since this happened. We are very confused as to why this would be happening - but he has started attacking feet, pooping on the floor, destroying furniture and jewelry ... and basically being a terror since he was neutered.

What can we do about this?

By "relapse" you mean Thomas was acting that way before the neutering? It takes more than 2 weeks before the calming effect of neutering starts to take effect.
If this change of behavior is new, better talk to the vet.

We had a lot of trouble with him as a young kitten, this is what I mean by relapse, but he seemed to have grown out of it and we were no longer concerned. However, since returning from his opperation he has been DRAMATICALLY worse, and we're not sure if this is his hormones readjusting or if we should be worried.

I would definitely discuss it with the vet. Sounds like he might be stressed from the neuter and the subsequent pain, and probably dealing with hormones and stuff leveling out as well. Have you tried Feliway diffusers?