20 years! 20 years I've known this person...what should I do? ?

My first love. I was 15, she was 13. I fell for her instantly in a time, when we didn't know what love was. But we dated and broke up. Over the years, we stayed in touch, talking, even getting together..sex..talk...someone to be there for one another...when we had no one. We always found eachother. We tried it the real way in 2002 and found.. both if us had issues we could not let go of at the time. But we still got together over the years..several times..for company..for what ever we needed to get through at the time. Recently, we got together...again..for the 5th time..and feelings were heavy for her. I felt for her too, but she has burned me too many times..her using me to get on her feet..and after a few sexual encounters, i never hear from her. It's been like this for years. She comes in and leaves and doesn't respond to texts, e-mails, calls...and wonders why i move away from her more and more each time. I'm always there for her..always been. I've been the friend in the relationship...where she's been the taker...the taker for granted in the relationship. Last time i seen her, was november 2007. After 4 months of talking and seeing oneanother, she stopped all of a sudden and used the excuse of her daughter being ill and her friend needing fake support of some kind to not contact me. And...i needed her at this time...i really did..for the first time in our relationship...and she wasn't there...as usual.

Today is her birthday. She is shacked up with some guy in another town...whom she met..while i was trying to contact her for the 5 months in 2008. I found out after i put it all on the line..she told me she met someone...and..i found out in july. All the stuff about her friend...and her daughter was bogus..she just didn't have the guts and the respect for me to tell me she found someone and kept me hanging. This is normal of her. After she told me, she had this huge boulder lifted and started to be my friend...after i told her she wasn't a friend. Not the one i knew. And she recognized this...and appologized. It's her birthday today and i have been ignoring her for 6 months while she has been sending me e-mails saying hello on my space, and e-mails and some texts on and off. As if she has some guilt by the way she has treated me. I want...to move on. Move on from people like her who took me for granted and have no respect for me what so ever. 20 years...what should i do? Should i send her an e-mail telling her happy birthday? She did wish me a merry christmas...and has asked about me a few times since, with no response from me. I think I've had it. But i need some advice. If i send her a text or e-mail, i leave this relationship open. If i don't, i close it. I told her in july when i found out...it's time to move on. both of us! I wished her and her daughter well, love and happiness and all. I have always been good to her. She's been really shitty to me. She just used me to bounce back from her depression and her lonliness until she found someone else. I know this now. And I'm tired.

What should i do? Please help. I have a few hours left before i decide.

Thank you.