The flip side of being a caretaker, and putting up with emotional abuse while carrying the financial burden as you described it is that it leads to resentment. So much of what you wrote resonated with me--the whole thing about him being "too good" for some jobs, while you throw yourself out there and do whatever it takes to raise your kids and put food on the table. It's not fair, and you're right to feel that way.
I've heard that resentment is a killer--literally. I'm not saying that you do feel resentful of the unequal share of the burden of the relationship, but I would, and I have.
I agree that you might want to read more about codependency, and other "extreme self-care" books like those of Cheryl Richardson. I used to roll my eyes at women who were assertive in communicating their way, or getting their mani-pedis every week, or posting pictures on Facebook of them and their SOs on a beach on an island, until I realized there is nothing at all wrong about them just looking out for themselves, and it makes life a lot more fun, too.
If you do decide at some point that you are not into commitment with this person, at least he hasn't done much to establish a relationship with your kids, so sounds like it would not be much of a loss to them.
Good luck to you. You do have tons of people here on this site who know exactly what you're going through, so keep coming back.