Sorry for the delay.
Okay, a few things first:
I am not your lawyer. I am not in possession of all the facts, we have not entered an attorney-client relationship, and you may well in fact need a lawyer that is licensed in your area. That aside...
I am a corporate and IP attorney who works closely with many startups. That in mind....
I couldn't paint a more absurd caricature of someone who is utterly unqualified to be a co-founder. A co-founder is like a married partner,and if this guy is failing to pull his weight even before the company has gotten anywhere, he is worse than a non-contributor, he is a toxic drag. His attitude is unbelievably shitty and he literally has nothing to provide.
A proper co-founder doesn't just demand stuff of other co-founders - I mean, that should go without saying. A co-founder has to supply something super, super valuable, whether that is mastery of the product domain, technical expertise, networking, money, or at the very least being a tireless ceaseless cheerleader and source of strength and support. This dicktoucher has done none of the above, and instead has just given you - the talent, the vision and the drive - a bunch of deadlines. He can go fuck a blender.
I don't know what anyone else has told you, but if people are advising you that you can have a binding verbal contract in regards to this, they can kiss my hairybits and I will gladly see them in court - they are fucking wrong. Any dispositive agreement over copyrights or patents must be in writing to be valid - and this is the situation in which we find ourselves. Additionally, in general, grants of equity in company need to be memorialized in writing as well. And not an email - an explicit, clearly governed contract.
The point is this - based on the very small amount of information you provided - I cannot imagine any meaningful legal claim this guy has to the ownership of the code or software you wrote or ownership in the company you are creating. So, think of it this way:
A. What do you owe him? B. What has he given you?
I'd say the answer to both is "nothing."
You sound like a very nice guy, but I think you are going to have to get a bit tough in situations like this, and tougher in the time to come, because it seems like you are allowing this guy to seriously, seriously guilt you with nothing more than a few emails when you have put in hours upon hours of labor and he has contributed absolutely nothing. I would seriously, seriously recommend finding an attorney you are comfortable with and running stuff like this by your attorney, because if what you are building has any value whatsoever, or even if it doesn't but looks like it may have value, people will crawl out of the woodwork to try and take advantage of you. And in this sitaution, your business partner is not your representative and will not have your best interests in mind. This is the role for your lawyer. So even if you find the perfect partner or co-founder who totally kicks ass, you still need a lawyer to make sure you are not getting fucked over.
tl;dr you owe this guy nothing and if you get more bullshit like this from other parties you should lawyer up. talk with four or five lawyers in your area for an hour on the phone - they shouldn't charge you for this. choose the one that sounds least like an asshole, knows what he is talking about and is very, very clear about how he bills.
You likely won't need to incur anything remotely like a big legal fee right now, but it makes sense to get a lawyer lined up for when you DO need to incorporate, draft terms of service, open bank accounts, hire people, sell your product, etc. Get that shit out of the way.
Best of luck dotcomrade. Come back to us and let us know how it goes.