(((HUGS)))
I'm sorry you're feeling so overwhelmed! With 3 kids, a job, and everything else you've got going on, it's no wonder you feel like you're ready to snap. You have too much on your plate, and your needs are being pushed to the bottom of the list.
First and foremost, I would say that in order to take care of those 3 little wonders, you first of all need to start taking care of yourself. This is by far the best thing you can do for them. If you are stressed and at the end of your rope, they will see and feel that stress, and take it on for themselves. They need a mom who is at her best, and if you're not taking care of yourself (with a healthy diet, plenty of rest, and a little down-time for your mental health), you can't be at your best for them.
Secondly, they need parents with a strong, solid, loving relationship. Your relationship with your husband will be the model on which they base all of their relationships. We all know that relationships take work, which means you need time for yourself and hubby! These two things need to be at the top of your priority list. If these are the only two things you can manage in a day, your kids will be just fine!! A house that is spic & span is nice, but it's not as important for your kids as two loving, healthy and emotionally stable parents. When they look back on their childhood, they won't be thinking about how clean the house was. They will be thinking about how much their parents loved each other and them, and how it felt to be part of a happy family.
Maybe you can start by sitting down and making a prioritized list of needs, for both you and DH. Are there things on your schedule you can let go of in order to make room for the necessities? Are there people in your life (family, friends, neighbours) that can help you take care of the menial day-to-day tasks, so that you can have more time for the important things, like nurturing yourself and your relationship? Are your children old enough to pitch in around the house, even if it is just picking up their own toys or putting away their own laundry? Are there other resources that are available to you that you are not taking advantage of, perhaps through your church or a community centre?
Instead of flying by the seat of your pants, write everything down - every task you truly need to accomplish in the day, and every option you have at your disposal to get them done. It's so much easier to put together a plan of action when you can see everything in black and white. Take advantage of everything available to you, and most importantly, do not be afraid to ask for help where you need it! Let go of everything that is not absolutely necessary for your well-being and that of your family. Let the word "no" be your new best friend.
Making a list seems like such a small place to start, but I assure you it's just the first baby step in getting your life and schedule under control. Don't think about this change in the bigger sense... it will be far too overwhlelming to deal with! Break it down into little bits you can handle (like making a list) and start there. Every little step you take that gets you going in the right direction will feel like a huge accomplishment. Setting these small goals and then achieving them will give you the confidence to keep going.
You can do it!!!!