It's really not that complicated.

He thinks he sent him the message, which he actually did, but it was on behalf of him, unbeknownst to him.  He used to have a thing for him, probably actually finds him cute, too, but he's found him.  He thinks he's probably in love with him, but so does he, who's got a secret admirer in the form of him.  It didn't work out between him and him, but what about him and him?  He's pretty infatuated with him, but little does he know he's the object of affection from him.  And he himself is obliviously part of a love-hate relationship with him.

Nope, not complicated at all.