Is it ever a good idea to be friends with your ex?

It depends on the ex. I have an ex-gf in France that I parted on good terms with. Whenever I go there to visit, we get together to hangout, have sex, or visit her family (who use me as the standard for all her boyfriends there after). Another ex-gf I have was a huge alcoholic and partier. I didn't realize until much later how toxic the relationship was and how unfaithful she was whenever I was not around.

I'm willing to hear your story and give my advice if you want. Friend and PM me.