We miss each other but im not ready?

hello. im 17 and me and my girlfriend have just broke up. we had a hugh fight last week we haven't spoken since. we were in love and i felt really guilty cos i upset her so much so i sent her an email asking if we could be friends. she replied saying she really missed me and felt guilty about the fight to. i think she wants me back. it was implied. im not sure im ready. it still hurts and im not sure if i could keep from hurting her again, not on purpose of course. how do i tell her im not ready for a relationship yet? maybe latter on but not yet?