I went through this with my ex as well, it was then I realized pretending to be friends or contacting him wasn't a good thing. He had hurt me a lot and I realized I couldn't be friends with someone like that. It hurt a lot to let go, but once I deleted his number, and IM names, and pictures and past messages. Even though the memories still haunted me and the pain was still there, it started to ease a little, I still break down a lot not because I love him though, but because he hurt me too much when I was already fragile.
For me the best way to get over an ex, is to realize somewhere out there, there might be someone who will love you and treat you the way you want to be treated. Of course I'm not much of an optimist myself so saying that seems hypocritical. But, a lot of people find their special someone, who says you won't? I don't know if things ended on good or bad terms with your ex, but when you are still begging for them to take you back it shows that you need to just let them go. Because if you don't, you'll never get over it, I'm not sure how some people stay friends with their exes, but I know for me such a feat is impossible, but mainly because they have all damaged me beyond repair.
I know it'll be hard for you to let her go, but you need to, just delete her and if you have her contact information memorized then you need to develop the willpower to say "No I won't contact her." The best way to do that is to think of all the bad things she did to you if she did bad things. For instance I would always think about how my ex used and lied to me, it helped me resist a lot better. If you can't think of things she did that hurt you then this may be harder for you. But if you ever need to talk, or want to talk to someone so you can resist talking about her, feel free to contact me.