Not all Slytherins are evil, nor all Hufflepuffs weak. There are caring, fiery Ravenclaws and twisted, cowardly Gryffindors. Your house is not who you are, it's what you value. Your house does not define you. You get to define yourself.
The last pinner said "It takes a hero to break a promise" Reality check: when I read about Dobby's death in the books, apparently I cry the same way each time. my hubby even has a name for it: the Dobby Sob. I cry "the Dobby sob"