I'm sorry his words came out the way they did. I can imagine how deeply they hurt you.
I'm trying to read between the lines here. There's not a lot of background, so forgive me if I'm overreaching in my interpretation of your situation.
Has he been unemployed because the two of you decided he'd be the stay at home parent, and now, he's feeling resentful of this (and possibly your new success)? Is he an author trying to write the great American novel? Was he laid off and unable to find a similar type of work? Does he have the requisite education and experience to work in the field he desires?
For a man with a wife and child to be out of work for 3 years, he's probably feeling very angry with himself as well as frustrated and helpless in not being able to get his career going in order to provide for his family. Sounds like some depression, possibly, as well.
Three years is a long time. I don't know what his career/field is, but it's time for him to re-evaluate and get some additional education and training. Or maybe get a completely different type of training or go back to school so he can get into a field where he CAN find a job. In the meantime, he should also be willing to take ANY type of work so that he can start building up his resume and his self-esteem.
If depression is part of the problem, he needs to make an appointment with his gp today to get a referral for counseling and/or medication. This self-defeating spiral has to stop, and he's the one who has to take action to turn this around.
Otherwise, it seems like the situation is just set for more hurtful comments and strife if he continues to feel badly about himself and takes it out on you and your son.
Maybe your husband was wishing that he'd worked harder to get his career established prior to having children, but if that's the case, he definitely chose the wrong way to word it.
The bottom line is your son is here, and your husband needs to get on board with that reality and do whatever it takes to remedy his personal problems so he can be the adult he needs to be. If that means taking entry level jobs and working his way up the ladder or going back to school AND working while being a parent, so be it. Thousands of people do it every day.
Please have a talk with him about this. It will only get worse if allowed to continue.
I truly wish you, your husband, and son all the best.
J. F.