Kristen, everyone here has been in your shoes. For most of us, heart surgery is very big thing. The anxiety we build up causes our emotions to be more volitile. A sad song or movie or a very joyful event easily sent me into tears. These are all experessions of the vulnerability we suddenly feel. A lady put cheese on my sandwich and for a moment I wanted to shout at her "NO CHEESE!!!!!!! I TOLD YOU, NO CHEESE!!!!". This is all very normal.
In the quiet hours you will have during recovery, as you start coming down off the emotional roller coaster, you may well find that the vulnerability that left you feeling so emotionally fragile can have unanticipated results. These experiences that expose our fragility, that force us to face our personal mortality often leave us feeling greater compassion for others around us. If you like quotes, and I do, you can't do better than Aeschylus who wrote:
"God, whose law it is
that those who learn must suffer
And even in our sleep pain that cannot forget,
falls drop by drop upon the heart,
And in our own despite, against our wills
Comes wisdom to us by the awful grace of God."
Larry