I find it hard whenever I hear/read a girl’s story of how bad the relationship is but cannot leave it because she loves him. I feel pain for her because that means to me she does not love herself enough.
If you truly want any guidance then start with the Loving Kindness (Metta) Meditation. Susan Salzberg originated it but you can find versions of it on YouTube. This will help you with compassion for yourself (as well for others).
You stated in the present tense that he is controlling, unloyal (does that mean he is dishonest and sleeps around?), immature, and treats you poorly. Is this someone who can love well? Is this someone you can partner with? As you said, the Cons outweigh the Pros.
I would really recommend examining why you don’t value yourself enough with your willingness to stay with him. I recommend seeing a therapist to help you gain a better insight on yourself on why you want to stay with such a person. Having the reason on not leaving because you are scared of starting over is not a good reason. I don’t think how you think what “love” is is sufficient. That is not love but co-dependence and attachment.
Focus on making your life better with school and other healthier relationships (not just boyfriends but friends).
Mark