You're not beyond repair, and you're not helpless.

Like you said: block him! If it's poisonous to have him in your life, then remove him from it. If he's blocked there won't be any drama as he can't contact you.

When you're done with your exams though, I WOULD suggest therapy. As it is right now, if you are suicidal I recommend going to the hospital. Your ex is NOT worth dying over, trust me on that one.

You say that you don't want to go talk to a therapist because it will take up your study time. Have you not considered that you have wasted a LOOOOOT more time worrying about your ex and avoiding dealing with the issue? That's also taking up your study time. Therapy might actually take up less time (in fact, I'm certain that it will take up less time, because it seems like you're spending all of your time consumed by your ex?)

It's ok to be angry and hurt. You weren't wrong about your feelings: you cannot help your feelings! And we aren't magic, so you can't have known what your ex was truly like or what would have happened. There's nothing wrong with you, you are just having difficulties with moving on. And that's ok!

I would suggest also just avoiding social media. Go to your school's library to study! Hide yourself in a little corner without internet access, and STAY there until you've done the amount of studying you wanted to do that day. Sure, you might drift off and think about things (who doesn't do that when they study?!) but at least you can't send him messages or stalk his fb page or anything. And then after a few minutes you can get back to your work. So on and so forth. Just allot yourself more time in the library than you're actually planning on studying for.