To me it sounds like you know this just isn't the right relationship for you. It's just a matter of how to end it, when and how.

You mentioned that it's not a great time for her right now especially with her studies, but in my experience there is never a "good" time to break up with someone. Unfortunately you're going to have to do it now because the longer you wait the longer you prolong the inevitable, which makes it hurt worse.

As for how, do it in person, be direct, phrase it as a statement, and remember it's okay to cry with her. In the end this is what's best for both of you. It's very natural to want to hang on to your first relationship, but trust yourself when you feel it isn't the relationship for you.

I'm sorry to say there is no easy or best way. It'll get better man!