Resident Cat Afraid of New Kitten?

I found a feral male kitten and he is about 5 weeks old. I brought him home and gave him a bath as he was riddled with fleas and ticks. Then I tried introducing him to my 3 year old desexed female cat. Well, that didn't go as I planned! Turns out my older cat is actually scared of the kitten. Her hair stands up on end and she gets the most terrified look in her eyes, then she bolts!

The kitten however hisses and growls at her. I just need some help. I'm trying to make them friends, but nothing is working. I've only had the kitten for about 1 week.
Please! I need help. I don't know what to do!

By Amber