My ex still tells me all his secrets?

We broke up almost a year ago (I was his first love). We're still good friends - he insisted on it. To this day, he still tells me deep things in his life like he always did... and I later find out that nobody knows about some of the things he tells me, not even his best friends at school. Yet when I ask him about his feelings, he says I would never be an ideal candidate for XYZ (list of reasons). We live on opposite sides of the country now, but there is a deep emotional intimacy. That confuses me. Can you really have platonic feelings for an ex while simultaneously putting them in a "best friend who I trust with all my secrets and feelings" box? He also keeps a souvenir from one of our dates on his backpack and carries it with him everywhere he goes. Another confusing thing. Yet he continually insists that there is nothing there.