Well, as long as you keep telling yourself "you can't" or you "don't know how" that is exactly how things will remain.
Your H will continue to become more aggressive about this divorce because it is what he wants. Period. It is hurtful but it is what it is. My H did the same thing.
At this juncture your choices are file on your H and that be that or let him file and sign. If you don't things will get very ugly for you and your son. You and your H can barely manage things with your son now... imagine if things were worse?
You have this amazing resource, a C, books and what I guess to be a very smart brain. It's time to use all these resources as stepping stones and not venues to wallow in sorrow. Stop reading the other board if you feel it brings you down! Stop surrounding yourself with things that are not helpful to your healing!
You have to want to heal and you have to accept (at some point) your H is not willing or interested in being a part of that. My H wasn't interested either. Not much else to really.