First of all, congratulations! I've had a similar situation (with less money) but still, I went through the exact same exercise. You have 2 choices basically, you can keep working or you can retire.
When I say keep working I mean working for someone. Let someone dictate your day, week and year. Some people need structure in life to function properly so if you're one of them, I'd highly recommend you to get another job at another company in order to learn new things. Ideally, you'd study a new position in between so you wouldn't get bored too quickly. Switch to Product, design, or dev for example. You're not chasing for high incomes so that allows you to come in as an "entry level". You seem to be humble so that could fit you well. But definitely look for new challenges since you'll be spending most of your time at work. There's also the entrepreneurial route but I'd put that into the second bucket.
Retirement. Unfortunately, unlike you, I could not simply retire from the 9-5 life. When I say retirement I mean not having to work for anyone. What I would do is to work on my own projects and take a year or 2 to explore different domains and ideas until I'd find something promising I'd be deeply passionate about. Needless to say you'd be learning every day.
In terms of what to do with your money? Here is exactly what I'd do personally. I'd put $5 million into government bonds with a 100% guaranteed return of about 2.5-3%. That would bring you about $150k of passive income per year for the rest of your life (based on inflation rate). That's it! I'd move to a not too expensive place and I'd still have $3 million dollars left. I'd actually split it in 3 in your case. $1 million for each of your kids. For each kid I'd split it like this: 50% into a more aggressive portfolio like stocks, then 50% into bonds. I don't know how old your kids are but the idea is to lock these accounts until they get old enough to understand the value of money. With your million dollar left, I'd buy a new house for about $300-400k. Then I'd leave the rest into a savings account to be used for fun, big purchases, etc.