I want to ask my boyfriend to leave the space in the library that I usually work in because I find his presence disruptive to my studying
Why do you want him to leave?
He just pisses me off and I flunked the test because of him.
Couples are expected to be able to get along together. If you need a space for yourself then let him know. He may be upset so try offering a compromise in order to get him to accept your request.
I wanted to stab him 12 times for being annoying the other day. I need to be alone.
Well if you feel like hurting him you need to remove yourself. Calmly sit down and talk with him about how you are failing and that you can't be distracted when you study. He should be able to respect your wishes.