I Have Self Esteem Issues

I still struggle with feelings of rejection, as a child i was rejected by my best friend. For two years we did everything together, one day out of the blue she looked at me and said your not good enough to be my friend. That statement haunts me to this day. I sometimes wonder if she realized how much her words hurt me and if she regrets how she never spoke to me again. I've never had a great self esteem. These issues have been carried into my current relationships. It's hard to fully accept that i am worthy of love.