For me it hurts because the highs I experienced with her I cannot reach again, and I am addicted to that rush I felt when I would see her.
I can agree with this, but conceivably if you meet the love of your life, someone without BPD and who will treat you the way you deserve to be treated, you can reach that high again. Mine would pressure me for marriage, started talking about kids, etc. She would still treat me like garbage but then get violently mad that I'm not giving her what she wants by getting married, never once considering MY needs and desires. The more I backed off of the subject, that madder she'd get. But she STILL wanted marriage! I tried to discuss money with her (obviously an important topic to discuss before marriage), and she'd complain that "I'm not discussing money with you because you're not my husband yet." Just a total mindjob.
They give you a rush, yes, but I feel that being with a more rational and sane person, someone who you could live a long happy and healthy life with, will give you that rush for the rest of your life and not in temporary spurts. I was looking at one of her exes Facebook pages (her ex fiance of all people), who has recently gotten married. He looks like a happy man. It shows me that there is indeed life after her.
Although, mine gave me that rush as well. We lived cities apart, and my rush from her came from showing me a new life in a new city that I didn't know existed. One that I came to love and wanted to be a part of. I feel that her being gone takes that away from me because the association has changed and been damaged.