***UPDATE***
the vet said to just let them sort it out, so that's what we did...
well they still get pissy with each other but they're getting along much better. they play like they used to, eat together, and when one wants some personal time it just hisses at the other and they go their separate ways.
thanks everyone for your suggestions! like many things in life, i guess this is just one thing you gotta wait out.