My friend who is gay is pissed at me.

Before I make my statement let it be known that I am in full support of LGBT. Sexual orientation makes no difference to me whatsoever, I judge someone by their character nothing else. Now, that being said, I am the only person my friend who is gay has come out to. He know I don't care that he's gay and thanked me for not caring. He also knows that I'm totally against slurs that have negative connotations such as fag, nigger, chink, etc. The other day after school he texted me and claimed (I say claimed because I don't remember having done it whatsoever) that in the hall I hit him playfully and said "fruit punch". Now, when he texted me he said "don't call me a fruit" and I had no idea what he was talking about. So I said "what?" And he told me about what he had recalled I did/said to him. I told him I didn't remember it and he got pissy and hasn't talked to me for 3 days (I have 4 classes in high school with him!!) The reasons I'm confused are because again, I don't remember having done it and I think he might have mis heard me if I did do that. And I'm also confused because he should know by now that I would never use the word "fruit" (I'm well aware of the negative connotations behind the word) towards him because It has male connotations and especially since I know he's gay! I've tried apologizing to him 4 times and he won't accept it and I tried texting him too but I get nothing. Also, my friend isn't always the best at accepting when he is wrong, and I really really think that he is in this case because A) like I said I wouldn't use that word and B) since I wouldn't use that word, why would I even hit someone and say fruit punch? It just doesn't make sense to me. I don't want o tell him he's wrong again because that set him off the first time but I feel weird apologizing since I think he is mistaken or I just really don't tenement having done it (but still wouldn't have used the word fruit towards him). Help?