A sad story about growing up and moving on, a necessary part of every life. Well written and touching.

The friendship may have been mutually dependent to an unhealthy degree--only you can say for sure if that was the case--but I don't see any of the elements that would make it a codependent one. Codependency is seen most typically in a child's relationship with a parent who has a severe mental illness, or the spouse of someone with a substance abuse problem. It's a complicated issue, but I don't think the term is applicable here.