Michelle it sounds like he is doing a lot of blaming onto you and it is not you. This isn't you, it is him. If he felt you were 'just friends' then he was the one that let it become that way not you. These are his feelings and he should take ownership of them instead of explaining what you did to make him feel that way. It was his choice to feel that way.
You said he was on anti depressants? Could they or the reasons why he is on them be something to do with his lack of passion?
There seems to be not a lot of point in discussion as he feels the need to defend his position and that makes him more rooted in it. Personally I would say, fine if that is how you feel I accept it. Then go dark, even over the puppy. You are being very kind to him at the moment and treating him like a friend reinforces his friendship idea in my opinion.
It is just me but i would just simply not respond to his ims and things, he needs to feel what his life would be like without you. It is his loss.
