Help!! It's been three days....

I recently (Wednesday) brought my cat princess into the vet to be spayed. When I brought her home that evening my male (Prince) did nothing but hiss, growl and swipe at her. I knew to separate them because he has done this to her before upon coming home from the vet. Although, the last time this happened it only lasted a day and they were back to being best buddies, they've lived side by side for the past 3 years!!
It is day # 3 and he is still really upset with her. I done everything from keeping them in different rooms, rubbing them with towels, letting them sniff each other....I don't know what else to do....any tips??

You COULD bathe them both.

Yeah, right.

Another trick to try would be to put vanilla extract (just dab, mind you) on both of them under their chin, on the back of their head, and at the base of their tail.

I am having the same problem as you.
Sasha was lap spayed last monday and Cleo hissed and growled.
Cleo is fine now but Sasha hisses at her now.
Oreo attacks Sasha now and will not stop.
I have tried the vanilla and everything.
I hope your cats get along.
Cleo did the same thing to Meeko after she had surgery a month ago and they are fine now.
We think her problem is because they used the same stuff on her when she was spayed in Nov.
She only does that if another cat has surgery.
If they stay at the vets nothing.
I have no idea why Oreo is attacking Sasha though.

Your female smells differently from being at the vet. You could wipe each of them down with a towel and put the towel where the other one hangs out. As another poster mentioned, you could also put vanilla at the base of their tails and at the top of their head so they both smell the same. Cats go by smell and that is why he is hissing at her. She does not smell like his "sister" that left to go to the vet.

We've been lucky that since our daughter moved out on her own and took Mika that whenever she comes to visit she brings Mika with her and when we go to her place we take Bijou. Yesterday she was over and Bijou and Mika curled up together in the rocking chair for a nap.

Thank you all for the replies. I greatly appreciate it....It is now day # 5 and things are much better. Prince is still a little hesitant with her but the hissing and growling has stopped however he still does the occasional hit.
I am still placing them in different rooms when I leave for the day simply because of her spay wound....
How much longer would any of you suggest I keep the separation up until princess wound is healed?