You are a patient kitty owner! Psyco is lucky to have you. My sister's cat has the crystal in urine problem, and she started feeding him a small amt of cooked chicken every day, she read that meat increases the urine acidityor alkalinity (can't remember) and since then he has had no problems. every couple of months he'd have to go to the vet for IV's, and it's been 6 months now with no vet visit.
I read that cats hate sharing their litter boxes, and you should have at least one more box than number of cats. If it didn't help psycho, maybe the other cats could go without fearing an attack!
I hope somehow he settles down for everyone!