OK...know where you are coming from! We experienced something similar in my household. If he's like my hubby (who is like most men), yours probably thinks that he works hard enough that ALL of his free time should go toward doing what he wants. Sorry, but they are very self-centered that way. Then plug you, the wife, in. We are just geared to jump up and start doing for others without thinking twice.
My suggestion would be to talk to yourself about what you are doing. Like, "Well, the supper dishes need cleaned up so I guess I'll get to work in the kitchen." Just say it to the air instead of directing it at him. If there is something else that needs done at that time, you could turn to him and ask if he could ___ (bathe/spend time with baby, get a load of laundry started, etc.) while you were doing what you're doing.
Also, I suggest getting involved in something w/other adults. Maybe just start once a month. Also talk w/him about how you really want to do this activity so he realizes you need some time too. If DH can't keep your son, then find a babysitter or ask a friend if they can keep him for a couple of hours (trade off child care to save $$!) so that you can go and do your thing and he'll see that you are more than just this person who works all day at a job and works all night at the house.
It won't be an overnight thing, and it does take some work, but keep plugging away and don't give up!!! Good luck!! You can do it!