I agree that Adam shouldn't risk getting back together with her. In fact, I have a policy of NOT remaining friends with ex-boyfriends. It's just too hard emotionally, and too easy to end up sleeping together again. Which of course leads to more hurt.
I don't think you wasted your time. I'm sure you guys had good times, otherwise you wouldn't have stayed together for 3 years. Besides, it was all a learning experience. You'll come out of this wiser and stronger than ever! That's how I try to think of it.
Having said that, I know it's not going to make it any better for now. It's gonna hurt A LOT before it gets better. There is truly nothing more painful than a broken heart. I'd rather get shot in the stomach sometimes, than have my heart broken.
So, Adam, take care of yourself. Six months from now I'm pretty sure you'll be glad it's over. I'm also glad you're able to find support here (and elsewhere, Myspace etc). We're here for ya, buddy!