You've had a hard time and some of their behaviour can be due to their early experiences but it isn't too late.
Definitely read How to Talk so Kids Will Listen and the Explosive Child. They will change your life. Ring HV about parenting courses, some have childcare.
But, you are going to have to put some major work in to get routines, order and a calm rhythm to your home. Wifi off for kids until things improve. Go cold turkey. Don't make it a negotiable, they are young enough for it to make a huge difference.
Lets say you got home at 5:30, have the next 2 hours planned. For example set up activity for boys to do together (crafts are great) at table while you cook, have dinner together, boys clear table while you tidy, baths, older one can play in his room while you read with younger one - stories are after teeth and a wee. Story, lights out. Then go to elder one. Will make it easier to do one at once.
At weekends get some meals made for making weeknights easier. Make 2-3 cottage pies, etc. Freeze the one you aren't using. Get a chore chart up and have a few chores the boys do each day at the weekend. Start having quiet afternoons where they are allowed one movie together while you have free time to do exercise video, read, have a friend over for a coffee. Make sure you get them out weekends to an activity that is physical and have a nice walk/park trip together. Will make a world of difference.
You can do this. Prioritize a healthy family routine, organization and some home and child management and it will get easier. You got this!