Why did he throw our 6 year relationship away for his boss?

OK, put your big girl panties on and wake up to reality. He was not your best friend, you were his best friend. You love the way you felt about yourself when with him, no one can ever be 100% sure of how another feels about them. Thus, he can throw your relationship away because he never valued it as needed to be happy. Sorry, but this is the truth. Also, if he ever did/does miss you, I can guarantee it was something you did "for him" that he would miss, not neccisarrily you as a person of value that he misses. Therefore, he sees no reason to apologize. You were never really that important to him. You just thought you were because he was present. As you can see, A man's presence in your life is no guarantee of love. You know a man loves you when he is into what makes you happy, wants to care for you only. Expresses his feelings freely...in some cases...or shows you by cooking, cleaning, nurturing, protecting, etc. In many ways a man can show love....AND IT DOES NOT CEASE TO HAPPEN OVER TIME. You understand? Then move on and stop telling yourself you love/loved him. It is not self-helpful to hold onto the hate or revenge-seeking feelings you are showing now. Let go and allow others to love you right now. The grocer, The elderly woman across the street, your family, any damn one who chooses to value you for YOU. Forget the zero and find a hero....if only in yourself. IT IS ONLY YOUR RESPONSIBILITY TO MAKE YOU HAPPY. Good luck.