I have found that as I get older, I tend to take everything in stride. Lifes too short to worry about every little thing (and I know its difficult for some people to grasp that). Its not that everything is meaningless, its not that there aren't important things to think about, but sometimes you gotta just not let them worry you. Focus on whats important, set goals to reach, and basically treat everything else that happens as fluff.
Look. I had a girlfriend of nearly five years straight up cheat on me, lie to my face about it, act like it was nothing big and she still picked him in the end. This mind you happened two weeks before exams, at which point there were a bazillion essays to write on top of study. Sure it sucked, but I just took it in stride, though to myself "welp there are more women out there, she doesn't want me clearly (much more to that) and I'll have some fun finding the next person in my life", got the hell over it and went on to get all my work done. It still stung here and there, but overall the point is to look forward. The past doesn't matter, its to be learned from. The present doesn't matter, as sometimes happiness can be fleeting. What matters is the future.
So think about all this bad shit for about ten minutes, then straight up don't worry about it and focus on the future (your exams).
and watch this, its great: