You should always keep a new cat seperated from established cats for at least the first week or so.
They will get to know each other through the door. Then a few days after that, switch the cats so that they can smell the other cat in the room the other was in.
ok i turned on some classical music... it should help her calm herself down... shes sleeping in my room since the other cat has the rest of the house... im kinda scared to sleep though she looks so sweet though
Hissing is normal, you have placed her in an unfamiliar home, with smells she is not used to. If you show fear or are nervous around her you could be bit. Keeping cats that do not know each other separated is the best way to stop territorial disputes from occurring, because she is pregnant, you should keep her away from the other cat until the kittens are born. Then get her spayed when the kittens are weaned. Then worry about introducing her to your resident cat.
i cant get her spayed till the kitts are weaned i will have to let her out b4 then... i cant have her in my bedroom for 2 months can i introduce her once the kittens are born or no? do i need to take her back to the other location..?
Sounded like she was due any time, if you don't know the cat, it is wise to keep her away from the other cat(s) in the home, because pregant cats due to give birth are a bit touchy (if she is a stray).
You should keep her in confinement at least for a week if not longer so the two cats can adjust to each other-
This article may help, it was written with stray cats and ferals in mind-