"when life gets tough it only gets worse till it gets better", why does the truth hurt so much?

one mistake turns in to a disaster and betrayal.. it doesn't make sense since then its been getting worse since i moved on its been brought up again.. its like i am not aloud to forget about it.. then for once i did think i had everything i needed for my heart to be happy, it all crashes before me.. why must i have to wait for everything to get better?