carbon, sounds like we are in kind of similar situations (thanks for the reply to my post in the other thread
i guess the thing is, even if he only sees you as a friend, then as a friend, he should not want to cause you pain. and you, as his friend, should not have to hide anything from him. honesty and transparency are important in any kind of relationship, be it a platonic or a romantic one. because if he is currently causing you pain, and you are constantly having to hide something from him (be it because of pride, fear of rejection, etc.) then this doesn't seem like a real friendship.
also, from the way you talk about him, he sounds like he really cares about you. you say that he always finds you when he is in need. i'm assuming this is not just a physical need, but an emotional one. so it doesn't sound like he's completely separated the sex (or whatever you're doing) from the emotions. that doesn't necessarily mean that he wants to get back together with you or give things another try, but probably that he is also a bit confused about he wants.
which is why you need to ask him where you stand. i'm not sure what the best way to bring up the conversation would be. if he lacks the patience to listen, would an email be better? in my opinion it's still better to do this kind of thing in person. in any case, i definetely think you need to find a way to talk to him about this. it's no use just continuing to feel frustrated! and the same goes for me.
good luck!