I am a college student with a cat I rescued from an abusive household. I've had her for one year and things have been wonderful until recently. My roommate graduated and took my cat's best kitty friend home with her and I had to move. She seemed really scared at first but I got her settled and she crawled out from under the bed to sleep with me. But then at four in the morning to this heartbreaking sound of her crying and pacing the length of my bed and body. I can't afford a second cat although I thought we'd be fine on our own. Is she just homesick or have I made a bad decision for my kitty?

Se undoubtedly misses her companion. She's also - from what you've posted - living in a new place.

Give her some time.

I'd give her a month, poor cat. My kitten took that long to adjust to me, my dog, my house. She had lived in a huge house filled with cats, kittens, and dogs.
Cats love enclosed places like boxes (maybe with a blanket in one) with just a round hole on the side. Put one by your bed, by your desk, by your couch. Some catnip, ping pong balls, pencils to roll around on the floor, and strings hanging from chairs and anything, to distract her.