I am mad I ever put myself in a position to have to rely so much on someone who wasn't really committed to US
Ok - THIS is the part you need to fix. Because even if he turned around on a dime tomorrow and stopped his affair - could you ever really trust him again to the point that you would let yourself be this completely dependent? It's ridiculous that you have to wait on him to see if you can do laundry or grocery shop.
So - let's say, whether your relationship is repaired or not, you need to find a way to become financially independent. Number one on that list seems to be getting transportation of some sort, both so you can get to job interviews and a job, and so you can shop for and provide for your son.
Would your parents be willing/able to lend you a couple of thousand to buy a beater car? Or can you devise a business you can run from home until you save up enough money for a car? What kind of work have you done in the past? What skills do you have? Since you are not married, do you qualify for any financial assistance? (Welfare, food stamps, etc?).
