I really want to die?

I'll keep this short. I broke up with my girlfriend who was the first person I loved dearly, more than my friends and family put together. It was all my fault we broke up as well. I ignored her for a month ago and I just started becoming friends again. Little did I know she now likes my best friend and he also likes her back. This is because he was the person "there" for her when she needed someone the most. I asked my friend if he was going to get with her but his response was "idk man, maybe, but not yet." What kind of ******* bastard answer is that. I was hoping for a "naw man ill back up." I also cared for her deeply after the breakup and I always regret breaking up with her. We were together for 2 years as well. I just came home during lunch today extremely saddened when I saw them hug each other in the loving way she used to hug me. I took her out of class before I left and told her thanks for being the best girlfriend ever, but I just cried through the entire speech. I'm at home right now and I'm so tempted to just take pills to overdose and die. I KNOW it's a painful process but I accept pain and the death it brings. I really want to do it, but at the same time I don't. She's fed up with me and will never give me a chance again. I missed her so much. I'm so glad she gave me the chances though. I wished i appreciated her more and loved her a lot more for she's a beautiful princess to me. So what do you guys think I should do? I already told them both my feelings and he said he'll back off but I doubt that'll last forever because I'm kind of ignoring him now. FYI I cannot move on from this. I really want to die. I haven't slept properly in a few days nor have I eaten. Death seems like the only solution. Pretty cliche huh? I know I'm a pathetic loser who lost his chance and should've moved on. But she was my gem. She was my life. She IS my life. I'd cut off all my limbs to be with her for one day. I'd do anything. I did everything i could to show her I was sorry, but she's just tired of me. I'm sure you all understand that tired feeling. So what should I do guys? I'm just so depressed. Thank you for anyone who actually reads my crap and comments.