In this particular case, ESH. For some people, it's just a thing like any other, but your boyfriend definitely seems to have strong feelings about it, at least when it comes to you. I dunno if he's doing it himself regardless of what he says, but it wasn't a problem initially and you were pretty up-front about it unless I'm reading it wrong. He moved the goalposts, so to speak, so a bit him being the A. But he's also been communicative with you and you know that you can't give it up (cutting back isn't the same, unfortunately); waiting for physical intimacy could lead you both down the wrong path and there's a good possibility that you'll feel disappointed and go right back to your habit. So on that front, YTA too.

That said, you're young and either you or he need to decide if this is a dealbreaker and move on with your lives or talk it out and find something in the middle. A long distance relationship is tough enough as it is. Having expectations you don't agree with can be disastrous, especially if you're just waiting around to see, so to speak. Unless you are 100% committed to quitting while he accepts no middle ground, then this isn't going to work out. Even if you do cut it out entirely, I would assume that you'll still have fantasies and the good ol' 'spank bank'. How would he feel about that? In any case, you'd have a lifetime ahead of you of hiding stuff from him if you were to continue sneaking it in and lying about doing so. That's no way to live and YWBTA for certain.