Problem help me please?

My girlfriend broke up with me last night. i was devastated and begged for her back. But now today...we got into another argument and it made me realize...this isn't the type of relationship i want to be in. I called her up and told her that i just want to be friends. She started hysterically crying and cursing at me. Asking me why, how, could you do this to me? After 2 years of dating! How could you do this to me after you BEGGED for me back last night. She had ME in tears on the phone. She begged and begged and begged for me to let things work out. At first i said no...but then i said fine we can try to work things out but the truth is deep down i don't want to try anymore. I don't want to make her cry i never intended on hurting her. I don't know what to do...i don't want to call her again tonight she's so upset. She thinks i want to work things out now. Am i giving her mixed messages? What should i do? I don't think i really DO want to work things out anymore!