What exactly is a broken heart?

What exactly is a broken heart? 

• forcing yourself to hang up the phone after you have dialed the first three digits to his phone number. 
• cold, chattering feeling you receive when you hear his name. 
• when you're crying yourself to sleep every night and yet crying more and more each morning. 
• glancing at the pictures of the two of you, and then quickly turning your attention to something else to avoid your tears. 
• screaming and begging for a second chance inside, but not being able to say it out loud. 
• the emptiness and heart wrenching feeling you encounter when you see him with other girls. 
• knowing that no matter what you do or say to yourself, you cant fool your heart into believing that you will in fact be "okay." 
• listening to that one song that makes you break down, on repeat. 
• when you go from smiling uncontrollably every time you saw him to quiet tears every time someone mentions his name. 
• when you try to avoid him but end up going out of your way just to get a glimpse of him. 
• when you know you've been hurt, but have no idea how to fix it. 
• when you finally realize that he's everything you need and at the same time realize he's the one thing you can never have.