I think it is difficult for friendships to survive sex unless you are both very grown-up, able to detach it from the friendship, etc etc
I'd say, generally, IME and from what I've observed, it's really difficult for a friendship to survive but most of the ones I've known have been drunk bunk-ups rather than pre-agreed no strings type stuff.
Having said that I know loads of friends female same sex friends who have had a bit and that seems to be quite easy to have it as just a thing and no feelings / problems / whatever involved.
Anyway.
He said he loved you, you had a shag, then he decided the shag was a mistake and he's been ignoring you ever since? He's just your basic common or garden wanker and an immature one at that.
How long have you been friends / were you very close, looks like you need to call it a day not least because he's not talking to you
but even if he did, well, he's acted like a complete twat hasn't he.
Sorry this happened.