You can create a routine starting tomorrow. It is hard to stick to a routine but it is important for many difficult children to have one. It will also help you to get through the day without worrying about what will happen next.
Set up a schedule. Schools have them and it may help your children. Have them help you make a visual poster of what will happen throughout the day.
Example:
Get up and get dressed
Breakfast
play in your room
snack
play outside or in family room
lunch
quiet time (books/nap/movie)
playoutside or in family room
snack
playoutside or in family room
pick up all toys
supper
family time
Get ready for bed
bedtime
Take a poster board, make a section for each activity and ask the kids to find pictures in an old magazine for each activity. Or take a few small poster boards and make up one for sections of the day (one on getting up and getting dressed, one on activities through lunch, one on activities through supper, and one on getting ready for bed)
It may be too big of a project to do in one sitting so you make the posters and each day ask your kids to add a picture.
The more calm you are, the easier it will be (just will not feel easy no matter what you do if you have a screamer on your hands). Take one moment at a time, you will get through this and your calmness will send a strong message that calm is how things should be. Kids can sense when you are uptight. It is hard for them to be calm when they feel stress in a parent. Try very hard to not let your kids feel how stressed you are. Put on a good front that everything is good because if they know you can not handle something, their fears will increase thus the behaviors you don't want will increase causing you more stress and a vicious cycle of everyone in the home on edge.
Then, make sure you find your own destressing activities when the kids are sleeping.
Let us know if there is a specific behavior you would like input on.
I can't see your signature anymore. I think your son has been diagnosed. Who did the tests? For him to yell, scream, destroy things at this age indicates there is something going on that he can not handle. He is not feeling well or can not handle transitions. Did he behave like this in school? Have you had a neuropsychologist test done to help determine the root cause of this behavior?