Hmm - this reminds me of a situation I got into recently while on a break with my dp (we have since got back together).
When single,, I struck up a texting "relationship" with an old school friend I had a mutual attraction to decades ago (we have very loosely kept in touch since as Facebook friends -this was the first time we were both single).
We live a long way apart, so a meet up was always talked about but wasn't going to happen in any great rush. Still, we have lots in common, and I was lonely - i certainly found it comforting to have someone to message several times a day, who would send me voice notes, life advice about the minutiae of my day, some sexual chat (never got as far as sexting quite) - it was all great fun, and i did entertain some hopes, though my good friends kept (wisely as it happens) telling me not to read too much into it....
Then, one day, I told him about a decision I had made that he objected to for ethical reasons of his own. (I don't want to say what it was as it's outing, but nothing major - I hadn't murdered someone or voted for Trump or anything - quite a normal day to day choice that wouldn't offend 99% of people). He sent me two quite aggressive messages disagreeing with my choice - I responded relatively mildly, but explaining my decision - and that was it. Haven't heard a peep from him since.
It did feel like a big loss at the time, though as it happens, shortly after that DP and I rekindled so it would have come to an end anyway, as it wasn't the sort of friendship one could have while in a relationship.
BUT - the reason for this tedious backstory (sorry) - I then found out through mutual friends that he is actually in a relationship himself, and had been the whole time I had been having these online chats with him. Full disclosure - I knew all along there was a woman he was "seeing", but had been led to believe it was a non-exclusive FWB - I have since learned that it is very much a full on relationship, and that though they are currently long distance, she will be moving in with him shortly!
So I assume that he needed to clear the decks, and looked for an opportunity to "get rid of" me, as messaging me, voice-noting me etc, while living with another woman, would simply have been impossible.
And I wonder if this is the case with your guy, OP? That his sudden volte face is not about you at all, but if he actually wasn't available to begin with?
Regardless, the way he has dealt with it, and the language he has used, is idiotic and repulsive. But look at it this way - he has done you a favour. Would you want to waste any more of your precious time, chatting to a twat?
But I know it's painful. And a disappointment.