Hey LostinTranslation. I know you've made up your mind and have already told him so. However, I worry about you changing your mind! In case you get weak, in case he comes after to you with promises and tells you all the right things (whatever that may be, whatever you may be dying to hear from him), don't go back!
For me personally, the biggest thing is the fact that he has already been intimate with you and never told you he was one of Jehovah's Witnesses. That's just insane. Of course he feels like he's leading a double life - he is! The ministry is the most important thing to a JW, and part of that ministry to talking to everyone about the religion - to neighbors, people in line at the grocery store, people waiting at the docotor's office - everyone!
The fact that he could disconnenct himself from that mantra, keep the whole religion secret from you, AND commit the worst sin possible for a JW (other than sinning against the Holy Spirit or apostacy), is just insane. It's hard enough for those of us that are mentally "out" of the cult but are "in" pretending because we're forced to for a family member. I could not even imagine doing what he's doing AND believing in the religion at the same time.
And I am not implying that he's really "out" or on his way out because he's waking up. He would have certainly told you if that was the case. And even if he does tell you such a thing, he's still very, very indoctrinated. And he did what he did (got intimate with you and kept his religion a secret) while he was still very much a JW.
We all here wish him well. But don't let him mess you up with his struggles. If he has to mess some girl up, let it be another JW girl that already has problems!