First of all, calm down. Worms are treatable if you get them in time and it's a good thing you noticed it.

http://www.thepetcenter.com/exa/worms.html

This will give you a bit of info on worms. Check to see if the one you found matches one the pictures. Yes, you will need to have the kitty dewormed and I don't understand that excuse given to you by the vet. Was this a vet that you've visited reguarly? I'm in Vancouver and there are lots of vets open today although I'm sure they close shortly. Could you at least get a sample of the worm and take it into the vet? Also, you could take a stool sample in to the vet for examination as well.

Sammy, I know that there are vets in our neighbourhood that are open on Sunday too. I'm going to open up my PM's and ask that you let me know where you live. I can help you locate a vet that's open tomorrow. Fast action is what is needed right now, OK?