When do you know... to let go

my worlds spinning.. and its not from the fifteenth beers i drank last night. Last night was it. I broke down. I ended things with Kevin. I know its for the best, but i cant help but cry every time i think or image it. my life now without Kevin. Our relationship lasted three and a half years, the first boy i ever actually loved, the first boy i let in. It all happened so fast, i was just laying next to him and couldn't take it and finally woke his sleeping body, tears down my face telling him it was over, that i knew he didn't feel the same about me anymore and that was ok, but i needed someone who is and wants to be still in love with me. He cried, didn't fight. I asked him to stay one last night with me but he said he couldn't and left. I grabbed my knees to my chest and cried the hardest i have ever cried and like a story he came back opened the door and kissed me one last kiss goodbye and whispered, "i love you" and left.  i woke up after felling asleep crying to waking up crying and as sweet and beautiful as our last goodbyes were i still cant think he didn't even try fighting... for us. which hurts the most. he just stroked my head asking me not to cry, trying to figure out if my break up was real or not, then finally realizing it was and sat up. we held every other for a long time, and then it was over. but the pain is not, and i know its is for the best but the tears keep coming. All the things we did, even now my best friend Lauren is coming over with a bagel and i cant help but think no more early egg sandwich's with Kevin, and i cry once more.  No more once a year trip camping and white water rifting which we had done with his friends for four years in a row, no curly locks of dirty blond hair to wrap my fingers around on boring days watching tv in my basement. When... when does it stop hurting. I know we had to brake up and even prepared myself, but then why am i not prepared now. not prepared for this heartache that seems to never go away. but i know, it was time... time to let go.