So it does sound like a bit of both, no wonder you're struggling, you're husband is too picky, but your son is also making a mess and being disrespectful at times.
Maybe talk to your son as well, and say you will only defend him up to a certain point, if he is leaving his mess everywhere and purposely being lazy/selfish towards other people in the house, you're not going to defend him at all, and you'll be putting house rules in place going forward for the basics, (if there was some effective consequences for his actions even better)
Same with your husband, say you will 100% back him up on certain house rules/consequences if he climbs down on some of the issues that you think are OTT, otherwise what's the point, it's not his way or the highway, he's not the boss of everyone, his standards are making everyone miserable.
Maybe at some point have a whole house meeting and try and clear the air a little bit too, do you guys do anything together at all? Sometimes when you work, come home, messy house, awful atmosphere, feeling unappreciated, rinse and repeat it becomes so hard just to be nice to each other when there's so much tension and resentment. If you have something you can do together, or they can do together away from it all, it may help to get them talking properly and enjoying each others company as people, or do you think they may be a bit too far gone for that now?
If your husband is up for it, get that dartboard somewhere in the house that you can all play on it together?