Unfortunately for you Dan you've betrayed her in the worst possible way.
There are some women who seem to be able to rise above, overlook, go round an affair, forgive, forget, reconcile and move forward, and stay in the relationship after they've been cheated on.
Then there are some, like me, for whom it is a complete deal breaker. The circumstances of it, how it came about etc. are irrelevant I'm afraid, it's the fact that the husband/partner has had intimate sexual relations with another female - be it once, twice, or several times. Once that has happened, it's game over and no amount of genuine guilt or remorse is going to change that I'm afraid.
In doing what you did, you have blown your own world apart, and unfortunately for you it sounds like your wife is like me and others, for whom sex with another woman is something she's just not able to get past, under any circumstances.
It didn't help that when confronted you told her a pack of lies. Maybe if you'd come clean there might have been a chance, but to stand there in front of your wife and deny and minimise, actually makes it ten times worse.
I also do feel sorry for you. It takes a lot of balls to come on here and write what you did and because of your honesty and the remorse and sadness that comes through in every word you write, the responses from MNetters has been gentler than they otherwise might have been.
But the fact is mate, you cheated and then you lied about it. Your wife is telling you in the clearest possible terms that for her, there's no coming back from that. There's nothing else you can do but respect her decision. It is you who betrayed her, after all.