Why is my cat scared of me ?

i have a female cat and a male cat, the female cat was sitting outside in the garden and theres about a foot of snow out there so i tried to get her to come inside so she wouldnt get cold, but when i opened the back doors she ran away hissing. a while later she came up to my bedroom window so i let her in, she came in but then she started growling. my male cat was lying on my bed, so i put him outside on the landing and shut the door because he is always chasing her and they really dont like each other, but then she was still growling. i tried to pet her but she started growling louder and backing into a corner of the window ledge, and then she tried to attack me so i kinda lost my temper and got an ornament and slid it along the window ledge. it only hit her tail a little bit so i dont think it really hurt her but she growled at me louder so i gave up. i havent done anything to properly hurt her so why is she scared of me ?