Ex's and friends

Is an ex always an ex or can, at some point, they become just a friend and drop the ex status?

My Xmas card friend for instance. He and I dated for about a year and a half in 8th/9th grade, so that's about 15 years ago. Since we've been not together for about 10 times longer than we were together, can he be labeled my friend instead of labeled an ex? I think yes. I mean he and I share history, there were lots of firsts in that history and yes I've seen him naked (don't judge!) (honestly don't remember his nakedness it was SO long ago). But since it was SO long ago and we share a great friendship, does that take away the ex status? The friendship we have now, while started because of our past, is now based on the now. Writing letters back and forth weekly over the past 9 months, finally being honest with eachother about life (I'm not afraid to tell him to put his big boy pants on and take responsibility) instead of being "polite", things like this are what our friendship is based on. I mean I do love him because of our past, but that is a small part, he's a beautiful writer and full of desire for great things in life, he inspires me with his relationship with God (not that I want one, but just to believe in SOMETHING ANYTHING awes me). He and I can talk about food, worldly religion, you name it. While I KNOW he's not perfect, he is still beautiful. When he's out of jail, I can't wait to be able to catch up with him in person, give him a giant hug and have a drink together.

At my friends wedding in November I asked the couples who were sitting at my table. I've known many of these people since middle school. One friend said her husband isn't allowed to have female friends. I've always had male friends, some of my best friends have been male. I'm very loyal to my friends, male or female, so I would have a huge problem if I was told I couldn't be friends with someone because of their gender. If I've known someone for ages and just because the man I'm with doesn't like it (when everything about the friendship is kosher) I would NEVER drop the friend. That is SO lame! I have a male friend I've known since middle school that did that me. His wife didn't like him to have female friends, so he won't talk to me now. It's the worst feeling, it makes me so sad to have lost a friendship like that.

So back to my question. Can an ex at some point become just a friend? Let me know what you think...