All those years you spent building up those walls, all that time, all that effort, it is amounting to nothing. All because one person managed to break through them completely. Now they're gone, but their destruction lies evident. It is in the way you laugh louder than anyone, cheer harder, hug tighter, for those are the ways you are trying to rebuild your defences. They are the ways you try to remind yourself that you are vulnerable, and that you must pretend to be strong once more. You're trying to refit the mask that is no longer sculpted to your face.
You're afraid of what they might all find beneath that mask; you're afraid that they'll all run scared. You're not as good a person as you seem, that one person made sure you show you that. They cut you and bruised you and toyed with you then left, terrified, when you began to bite back. They'd pushed you to your breaking point; even a saint's patience has a limit, and you sure aren't a saint. They were too cowardly to face what they'd created in you and now you're left, alone, lonely, seeking something you don't understand.
You'd flee back into the arms of the person who broke you, even though they despise you, with an undisguised hatred. You must understand; they cannot look at you because you reflect who they are. They hate you because you embody all that they could have been, and all that they take away from themselves when they hurt you. For every time they beat you, they'd rejoice, for you are one who shares in their lonely pain. But they've left you now, because they couldn't bear the thought that the fault of creating another like them lies with themselves alone. They look at you and are reminded of their own evil, of the person who hides behind their own mask. Only the truly good can bear to be stripped naked of their façade, and they are always too modest to do so. Remember, you were one of them once, before that person got to you.
So in a quiet moment, reflect upon everything; recall who you were, wish for who you could be, vow to start living once again. But don't close your eyes, because all you'll see is the face of the person who broke you.