I haven't read the longer replies here on the second page, its getting late but wanted to reply before I headed to bed.
It can be really overwhelming when you feel like things are out of control. I really feel for you. I have had similar issues before mostly with my oldest who is 8 & also lack of routine.
A few things I would like to suggest are firstly.. have you had DS 2 (sorry trying to keep track is it the 9yr old or the 5 yr old?) who freaks out about not having the right cup etc assessed for anything like Autism/ aspergus, or maybe even anxiety? Have a bit of a google & see if you think it may apply & if so get some help ASAP.
Next, yes try really hard to get a better routine in place. Get DH on board & ASK for help. One of my big problems was I would harbour resentment because things I couldn't get too where not getting done but then I realised I never actually asked anyone to do it. It seemed crazy that I should need to ask but really my DH is just a bit oblivious to the things like washing on the line that needs to come in but I am not home till it gets dark that evening as I am taking kids to karate for example. So I would fume on the fact he came home to am empty house & sat on the computer till we got home. But now I just leave a note if there is something I need done before I get home.
My routine sucks & is a working progress I am struggling to get my kids into some sort of routine of jobs they can help with. I get the ****s at the lack of effort & just do it myself as its "easier" but really I am not doing them any good by doing this but finding it hard to break the habit.
Also, you & DH need to work on what ever the issues are you have. It sounds like an unhealthy amount of fighting between you two is happening Maybe you could try writing it all down & asking DH to do the same & have a read of what you both have to say but only under the strict understanding that it doesn't start a fight. Seek some marriage counselling if you really feel you need some outside help.

One ting I did recently was a triple P course. Its a positive parenting thing. It was amazed at how much I think it has helped, just by watching a DVD. I have a copy of it on my hard drive & if I can get it to burn on to a disk or USB I am happy to send you a copy. One of the things that really stood out for me was what they call parent traps. have a read http://www.triplep.net/cicms/assets/...00gr5so127.pdf another useful page to have a look at is this one http://www.triplep.net/cicms/assets/...00gr5so183.pdf I know it all seems like simple common sense stuff but be honest with yourself when you read it & just ask yourself, Do you really do all of what it suggests? I think i am a good parent & I can honestly say that I hung my head in shame for a fair bit of what I read/watched while doing this.
Here is a link to the main page Triple P - For Parents

But overall, don't beat yourself up. Please don't get angry at your kids. If you stop yelling, they will stop yelling too. remember that you & DH are a team & it sounds like maybe you doing a fair amount of the work here. I understand that our hubbys work & are tired when they get home but its a team effort & with out that help then things just don't work they way they should.

Another thing, take a step back & look at each of your kids. How old are they? do you think your expectations are too high for their ages? This was something I was doing, I was expecting way too much from my oldest. He is a mature young boy but really he is only 8. So sure he may act like a 16 yr old at times with his tantrums & fighting etc but he is only 8, He is a child. I needed to take a step back to realise that. I have gone from having a child who fought with me constantly every day. Physically fighting me. To a having a child who is more "normal" & even asks for a kiss & a hug each night before he goes to sleep! The triple P thing hasn't fixed every thing like magic but it sure as hell has improved things greatly & really its not about disciplining your children with harsh rules and consequences. its more about looking at yourself & the way you say & do things. One of the good ones that I found applied to me was Being more descriptive in your instructions. the example is a little girl jumping on her bed. Mum walks past the bedroom & says "Stop being so silly" and walks away. Girl keeps jumping on her bed. Mum comes back & goes off because girl is still jumping on the bed. But the thing is the girl is all of 7 maybe. Sure she may know that Mum means don't jump on the bed but she never actually said that. So what is suggested is that Mum next time says ' *name* Please stop jumping on the bed, it is not safe. How about you jump outside on the trampoline" (or other alternative)
The point being that kids need clear instructions. You point forms & remind them. Please put away your clothes could be Could you put away your socks & undies. When you have done that, could you put away your school clothes too. KWIM?

Let me know if you would like a copy of the DVD & I will try & get it off to you. Send me a PM if you like.

Hugs, stay strong & just remember to breath. Don't try & fix everything at once it will take time.