Why it feels like end of life after a breakup:-((?

Have you ever been dumped so cruelly? Why do you think like your ex was your oxygen/air and now you are alone in some painfull black-hole without her? Why do you think your ex was the only one? Why is it like a STRONG drug addicion? Why we think like we cant breath when we are going to bed and turning off lights? Why does it hurt like hell that nobody or nothing can help? Why this all? And what to do? please..:-((