Having 1 less adult in the house is hard for anyone, let alone someone with ADHD!
First thing- go back to treat your ADHD with a Doc familiar with the diagnosis. I was floored when a friend who’s a radiologist (her husband is an anesthesiologist) said “There are subsets of ADHD??”. So many people don’t know the difference & treat it all the same. Skip those folks & your GP too if he/she has no knowledge of it. The rest will be more painful if you don’t start there. I was in your shoes. It nearly set me over the edge. Fast forward 5 years and I know can almost push the work load of my team of 5 assistance (at work) completely by myself with one more child and a vacation rental to manage to boot!
Please never feel bad asking for help. If this was your “out of house job” you’d have to delegate. Home is no different. Don’t forget to utilize your kids to help. I’ve found GREAT nannies on care.com, craigslist (found one we had for 12 yrs!) & other places. Absolutely call friends for mother’s helpers. Frequently other moms are the best with sharing this info- “so & so is looking for a new family”, “we don’t need ours as much and want to help her find her next family…”, “had a terrible experience with X…”
Don’t beat yourself up. You can do it, but make a list and commit. It can be as simple as a pad/paper, your iPhone Notes or Reminders apps, Any.do, Trello, etc. There are great tools out there to help. You can do it! If a school trusts you to teach kids all day long (teachers are my heros!!!), you can pull it together at home too!! 😉