"If I could find a way to see this straight."
Blaine was getting angry because Sebastian was trying to blackmail Rachel and no one was doing anything about it. Dalton, the school that was once his safe haven, his safe place, is not doing anything to help him. They're not even punishing Sebastian or any of the others for what they did to him and he doesn't believe they will do anything now. And all of it is making him angry, once again nobody is listening to him, nobody is hearing him and he's losing his faith –again.
"I'm losing my mind losing my mind losing control."
He feels powerless, like there's absolutely nothing he can do, thinks that no one will understand how all of this makes him feel. And it drives him crazy, like he's losing his mind, losing control - as anyone would feel at that point, he assumes - and Blaine hates not being in control.
"Life's too short to even care at all, oh"
He knows life is too short to care about stuff like this, tries to stay calm, cool and collected because that's just who he is or at least who he'd like to be and he's just searching and reaching for the good things in his life, like Kurt and music, to help him through.
"Waiting for this cough syrup to come down"
One more spoon of cough syrup right now.