new kitten makes older cat aggressive to owners as well

My roomate has a 4 year old spayed female cat and yesterday I bought a 2 month old unspayed female kitten. I brought the kitten home and they briefly saw each other when I took the kitten out of the box and the older cat reacted by hissing and running away. I kept them seperate the rest of the day but the older cat was very stressed to the point where she hissed and lunged at me, and then when her owner (my roomate) came home , I tried to make friends with the older kitty but she hissed at me and then continued to hiss at my roomate as well. The kitten doesnt try to interact with the older cat she let the older cat call all the shots. The older cat has always been very passive and friendly towards everyone and her extreme behavior is really frightening. Is there any advice for me?? I understand that the cats meeting needs to be very slow and gradual but Im very worried about the fact that the older cat is soo aggressive towards people now...

The resident cat is on guard now and will be for some time. Do not attempt to pet the resident cat or pick him up. You introduced the two way to soon and now you have to help the aggression die. Pick up a few feliway comfort zone room diffusers and plug those in. Keep the kitten in a room by itself with lots of toys, food and a litter pan. Make sure you have a cat condo or something the kitten can climb in the room-

here is an article

Introducing cats