First it is true that it is near impossible to disengage in every single aspect, especially as a custodial sm like your are. It is possible to find many areas where you can engage and that alone will help. When it comes to mess if the kids are leaving little things around the 8 mo old can get into come up with a plan with your dh. Let him know you will be disengaging from mess issues due to the kids inappropriate behavior and it is best if he follows through on this. Make it a team thing. Decide what that will look like. Perhaps you will ask the kids one time to pick something up, if they don't it goes in a big bin that you set (dont' dramatically throw) it in. When he comes home he is given the bin. He may elect to keep the items in that bin for one week or something like that as a consequence for the items not being properly taken care of. If the mess is of a nature that it will not be a safety hazard to your baby then let him either reinforce the kids handling it or do it himself when he gets home.

I would also look at what are reinforcers for these boys? For example do they have a game system (or something else) they like? Game system goes with dad now or is locked away until one hour before bedtime. If their conduct has been acceptable it is brought out at the end of the day as a reward. If the conduct that day is not acceptable they miss out on what they like and will have to try the next day to earn it. Now, when doing something like this you need to reward improving behavior because they too are trying to break bad habits. If their behavior is usuall at a 10 percent and after they try they get it up to 50 percent, give them some degree of reinforcement-maybe 20 minutes on the system. After a week they need to up the behavior to 60 percent and so on. If they have to be perfect with no slips for reinforcement they will get discouraged and this system will not work. Inform the kids ahead of time what is happening-kids you will be given one reminder by vigil to pick something up, thereafter it will go in a bin and you will lose it for a week or kids game sytems are a privilege not a right. These are the expectations of behavior (write it down and keep it simple-3 of the most important things to start). When we see you are working hard at improving these behaviors you will be granted some time on the game system.

This will not work overnight,they need consistency and to see both the consequences and rewards. Make your home a no cussing, no negative conatct home from this day forward. That means the expectations are neither they, you, or your dh swear, slap, or hit anyone. No looking for validation on this board to tell them I'm not taking your shit. You are taking yourself out of this game and showing rather then threatening from now on. You two will need to be the example here and stick to it. They are way to old for the do as I say not as I do method. You and your dh have given them rewards for their behavior that have made this really fun for them and that needs to stop now. They won't wash the dishes? No more watching Dad and vigil rant and rave and slap and scream in an attempt to make them follow through are gone-the days of pulling the parents strings to see how hyped up you can get them are gone. You find those things that mean something to them, give them them the expectation and then follow through on the reward or consequence. The dishes may not get done. The consequences is not the adults pushing the sitaution to a frenzy til it gets done it is following through on the consequence. You very well may do the dishes yourself and later when they want to do the thing you identified as a reinforcer they just don't get it. The whole time you are very direct, calm voice, not a lot of talking. Just matter of fact, you didn't do the work you don't get the reward. Just like in the real world-you don't work, you don't get paid. It will take some time but they will catch on.

You have identified that one of them has anger management problems. Get him into counseling. He does not need a diagnosis, he needs anger management skills training and you can all benefit just from blended family counseling.

Vgill have you truly spoken to your dh. Truly told him that your coming to the end of your rope here? Having an 8 month old crawling and having those two be the way they are .....
How old are they?
Next year for xmas give them a lump of coal. Serioulsy...give them nothing.
Your dh works 16 hrs and physically cannot enforce the rules. And you guys need the money to support this family. Honestly, either he severly punishes them or get them removed from your home.
If your dh is gonna work 16 hours, and if they wont listen to you, and they've hit you, call the police and have them removed.
If i was at my ends rope , i would tell my dh, get them out of the house since they do nothing.