cat people...please help

we just got a new kitten last night.....my older kitten who is about to turn 1 is NOT HAVING IT i know it hasnt even been 24 hours yet but it a little scary. She looks at the new kitten and hisses so loud....i have NEVER seen h er hiss until yesterday when we brought the kitten home. When i was living at my moms there were 2 other cats she didnt see very often but when they came downstairs ( my brothers cats) she wouldnt hiss or anything she just wanted to check them out. I am worried that we will have to bring the new kitten back if she keeps this up. She wants nothing to do with me i cant even pet her she just btes me and walks away i have had her almost a year ( she was 4 weeks when i got her) and its sad that she is mad at me lol but i want her to like the new kitten. she has not gone after her yet or tried to pounce at her she just gets a nasty hiss and look on her face like she wants to attack it. Is there anything i can do to get her to adjust to the kitten better or just have to wait and see what happens?? thanks so much

I sympathize with you! It's so heart wrenching when they are mad at you! If it's just hissing that she's doing, she will get over it. My older girl (and she was OLD - 14) had to deal with us bringing home two new kittens and shortly thereafter another new kitten (they were rescues and my crazy cat lady of a mother went loopy). She was NOT happy with them or us! But after awhile she learned to just deal with them. The problem with kittens is that, like children, they need to learn their boundaries. Once your new baby realizes the other cat is the boss, things will calm down Another thing, make sure to continue to show your older cat as much if not more attention! She may feel a little bit slighted watching you play with the new kitty. Good luck!