Kacee, my heart goes out to you! I get that it's hard for you to fully let go of this marriage, even though it has been 2 years since he left and a trial reconciliation didn't work. If you can step back a bit, though, and look at things more objectively, I think you'll see you already are "divorced," hon, and have been for a long time - just not in the legal sense. As granjura suggests, I believe it will be better for you to be fully - legally - divorced and free to begin a new life.
TG, you seem to know what you need to do financially. I agree that you can't count on what your X promises today - things change. Nor do I see why you should remain dependent on this man to "maintain" you, financially, for the rest of your life - especially when, sadly, he left you for someone else.
IMO, others have given you very good advice on that - the best of which, I think, is to seek professional legal advice. Your X, I'm sorry to say, is trying to control the situation. While I know he doesn't want to hurt you (anymore than he already has, that is) and probably means well regarding the finances, it seems to me he is, mostly, trying to do what works best for him. You need the chance to set things up so that they work well for you, too.
I agree that you should try to keep things as amicable - and I would add, as simple - as possible, for the reasons that others have given. However, I think you need to take a stand for yourself, however amicably.