Why didnt he value me or our friendship ?

hi please can i get advice a guy ive worked with the last 18 months is leaving in 2 days. he as emotionally and physically drained me with helping him with personal trauma and financially and of course work. i got him through all his assessments, have been there for im always and have never let him down. in return hes let me down, lies friequently, doesnt care that i pay every break for lunch and doesnt seem to give a damn in general, yet when he started was over me like a rash-probably because he knew i was a sap and needed help from me. i feel so used and yet so upset. i genuinely cared for him and thought he was a friend . i even sent an email saying how hurt i was that the friendship has soured but not even a reply and now hes going in 2 days -yet i feel like the bad guy ! what the hell did i do so bad apart from trying to aid someone in need pls advise :(