Can I tell my friends GF about his ex?
Why would you talk about your friend's gf's ex?
I can see that he's not over his ex and I just want to give him a sense of reality
Whatever your friend is dealing with in regards to his ex, it is not your business to start talking about his gf's ex just to point his own relationship hangups. Stay out of your friend's relationships and focus on your life.
What are you trying to say about my relationship?
I don't really know what is happening in your own relationship I just know that you should not insert yourself in what is going on in others' relationships.