Gosh!!!! More of these type of guys!!!! I wish I had a kind of spray to wipe them off the planet!
If he tells you that he wants to "be friends" with you, it might just be a plan of his to keep you as a sidekick, just in case he can't find somebody else OR to use you whenever he feels like it. He KNOWS you are not over him. He WILL take advantage of this.
Truth is, they don't really mean to stay friends with you. They don't think that way at all. Only women think like this. Maybe he tells this to you to "soften" the situation or because they feel guilty. Little by little they distant themselves until they finally cut off communication completely.
If there is one thing guys do hate is "over-analyzing" a situation. STOP hunting him down in your efforts to try and "be friends". This causes him to suffocate and get bored with you. I'm pretty sure he sighs every time he sees a call or a message from you. You, on the other hand present yourself as too desperate.
KEEP YOUR COOL. You have other friends too and even if you don't go get yourself some!! Don't show him that he's THAT important. Don't feed his ego. Let him be. If you see that he is not communicating with you, FINE. Move on, fill your life with activities. Get busy! You are an interesting person and you do interesting things. Make him regret his choice of letting you go. Don't focus so much on this one lousy person when you can fill your life with so many other people. Give others a chance.
You will always feel weird when you see him with another person. You will always wonder, "why her and not me?". Cut him lose. Step away and with time you will see that he wasn't a good choice for you.
Now, go out. Get out of the house and start making new friends!!!!