M.B.
You definitely need counseling. It might also help for you to read the book: "Act like a Lady, Think like a man" by Steve Harvey. I thought I understood men until I read that book, but the author says it pretty succinctly that there are 3 things that men need in a relationship and sex is one of them (it is 3rd on the list after support and loyalty). It is one of the most important things to men - that's just how they're made and he absolutely says that men will go elsewhere if they don't get "it" at home.
I totally understand how you feel, but it does take two to make things work and unfortunately, IMHO, women have to do more of the work in this area, just as we do in all other areas (home, kids, etc.). One thing the book says about men is that until they have achieved the level of success that they desire, they cannot function well in a relationship. So, you might consider that your husband has issues at his job and as much as we might not like it, men really do need someone that they can talk to about work (i.e., Support) and most of them want to talk to us about it because we tend to be more sympathetic and they don't have to show so much bravado to us. Also, his increased need for sex may be his way of decompressing from the issues at work, BUT that is wrong as he is using you in that case and the situation is clearly not meeting any of your needs.
So, you do both need counseling and unless he's willing to admit the wrongs that he has committed (as well as you), then you will continue to have difficulties and these problems will only get worse. And as you say, that situation is not good for kids. One of my favorite quotes from Dr. Phil is that "the only thing worse than coming from a broken home (for kids) is being raised in a broken marriage". So, you both owe it to your son to improve the situation or decide that the situation isn't going to improve and move on. I think many of us can live with having failed at marriage, but failing our children just isn't an option.
The 3rd thing the book says men need is "loyalty" and men will start disconnecting if they feel that you aren't willing to stand by them, if you will. This might again go back to work issues, but it seems that this may also have to do with differences in parenting styles or what's important in your family life (i.e., his "you don't want to do what i want to do..."). To me this also has to do with men really being big babies and they do not take criticism well - it's the same theory to me as the fact that positive re-enforcement is a far more powerful training tool (for husbands, kids, dogs, cats, whomever) than punishment.
BTW, the 3 things the author says the 3 things women deserve (or should expect) from men in a (good) relationship are: 1) Professes his love (theoretically since you're married, your hubby did that long ago), but I think that sentiment can die if it's not nurtured 2) Provides for you 3) Protects you
Now, before the feminists get in an uproar, I really think that this is true in terms of how the man in your life treats you and isn't necessarily saying that women should entirely give up control to men - indeed he is very clear in saying that women are in charge in a marriage - men just don't like to admit it.
One of the most important things is how he treats you around others - does he praise you or is he hypercritical or just doesn't seem to care. Also, if he is not wanting to protect or provide for you, then that is a red flag - he really does not care about you that much. And, one of the things he says is that men should NOT have their wives on budgets and wives should not have to ask for money to buy groceries, kids clothes, etc. - since women are responsible for the majority of household buying decisions, they should also have control of the moeny. Men should be more than willing to provide for all these basic needs for the family.
Good luck and your recognizing that this situation is problematic is a sign that you know that things MUST be changed in some way, which is a very important step in improving your life and that of your child.
And, I really, really recommend you get the book as I've really just summarized and there are lots of nuggets of wisdom - the author refers to it as a play book for women in dealing with men and it contains info that men wouldn't really want us to know because it can really give us the advantage we need in relationships.