I'm going to go with the pragmatic route here.

Everyone always says "choose family over your job" as though the two aren't very much intertwined.

If you have no job propsects lined up, you suck it up until you do for a variety of reasons. A) Unemployment could very well lose you custody. B) Being jobless is an incredible stressor. While you'd like to think it won't effect you, it certainly will. At that point, just how happy could your time at home with your kid be? And nut-cutting time won't be too far off unless you've saved well.

Tiger may be right that your kid doesn't really care, but you will. The pride of being a provider cannot be overstated and the loss of that status will hurt you more than you realize, IMO. You'll see the things you can't do for your son any longer and it will eat at you. Maybe resentment creeps in, maybe it doesn't; but stress will and your life at home will not be what it once was.

If you want to prep some resume's and start job hunting, well that makes all the sense in the world. But to tell your boss to shove it without having any idea when/where the next job will come from ranges from shortsighted to blatantly irresponsible. Take the extra hours for now and start looking for a new gig. Worst case scenario is another few months with extra hours but that's a hell of a lot better than unemployment and cold-calling in this job environment.

I don't know. Can you?

Is it going to be that your boss wants to raise your hours? Or make you choose between the job and your son (i.e. fired/quit)?

If it's the first one....find someone who can babysit. If it's the second....find another job.

Just me but, I would have a sit-down with the boss and address your concerns with him, or her. They should be able to present an option that works for you and them as well. That way you will know PDQ if you need to start looking for a different employer. In any event, the best of luck.

tell your boss that not only are you picking your job over your kid but you've invented a new pizza that he needs to try now. sprinkle the anti-freeze, serve, wait an hour or two then take your kid to the movies.