Should I keep talking to my ex?

I was with a girl for five years and we broke up a month ago but I realize now that breaking up with her was the biggest mistake of my life, but she won't take me back anymore. I figure shes not over me completely either because the last week or so I finally got back into touch with her despite promising I wouldn't and we've talked for 4-5 hours on the phone everyday which actually helps me get through the day and I feel better afterwards. I know its normally advised not to talk to an ex at all in order to get over them but I've known this girl for five years and we shared everything and this past week was the only time I've felt a semblance of normality since we woke up.

My long term plan here was to keep the emotional closeness while finishing my degree and getting ripped and eventually get her back one day (in the meantime I still plan to date other girls).

Thoughts?