I have had a horrible cheating-breakup phase where every minute of the day was painful to go through. The only way I could make it was to smoke everyday till I passed out and slept. 
The days I wouldn't smoke, the emotional pain becomes surreal. Too real that my heart starts aching physically. It feels like it is being crushed inside by someone or something like a squishy toy whose purpose is to be crushed for pleasure. It gets so painful that I feel the rush to take a knife and cut over my chest, pull the heart out and hold it in my hand to help it beat better, make sure no one is crushing it heart from inside. I cannot even breathe at these times. I feel I am chokin on my own heart that is already being crushed.