Feigning indifference is your saving grace. It's when you give that cold-shoulder that you can face anything or anyone. If you can convince the person on the other end that nothing ever meant anything to you, you can get through just about everything that comes your way. That 'Heartbeats' lapsed you to tears, is your secret and the knot in your chest which refuses to come undone, is for you to withstand.
There's a sense of comfort in knowing that the person who caused you to falter and left you unsettled, won't get to see you in that disoriented and disgraceful state. It's caitiff in the least, agreed. But if you have to go through the inescapable motions of grieving and affliction and regret, you might as well do it in the quiet of your room where no one can see that smudged kohl or hear that heart-wrenching song which reminds you of the time spent unscathed and then of everything you did wrong, of every moment in which a choice was made, of every expectation you said you won't have. You can't help but think, 'what if I hadn't gone through with it'.
God forbid anyone saw you this way. You who claimed to not care, claimed to be on a different level of sensibility, claimed to be in control, claimed to be detached, dispassionate.
And now you snivel while the song plays. A girl can only do so much.