I'd buy the relatives I trust and care about a house and car, nice holiday together.
That's Dsis 1 and her family, trust fund for nephew, 2 DBros, dad, my GPs (who would probably try and refuse anything - no you will take my money you selfish people
). Probably it from the family, I don't trust the rest. They will fall out with me/bitch about me etc etc so they get fuck all with my millions .
ILS get exactly the amount they have helped and contributed to our lives, probably about a tenner each.
Sorry DH (but he would probably agree with me).
I'd have a house, not too big, good 5/6 bedrooms.
Another child (DC3)
Housekeepers/cleaners/chef
A horse and someone to look after it
A collection of sports cars
A villa in Florida and maybe Spain or somewhere like that
Some nice holidays, spend the summer travelling America
Private education for the kids and trust funds for when they are 25
I'd be well groomed at all times, go to the salon once a week for facials, nails, hair etc.
Fuck off big shopping spree in somewhere like New York, Paris, London.
Let the kids go a little bit mad for once, choosing some toys.
DH would want various rooms dedicated to memoribilia (like Star Trek, Liverpool etc
, guess who isn't having control of the money)
The I'd live off the interest and give to various charities. Probably children/animals and research into certain illnesses that have affected me.
I have thought about this a lot.
Oh and I'd help 1 friend who always has shit luck. The rest, I actually wouldn't as life has taught me that friends don't seem to last so I don't want to waste my money on them. Before DH and I said we would buy a big community so all our friends could live in one place, then we stopped talking to many of them so it would have been awkward having to live with them, glad we didn't win a couple of years ago. 
Oh and OP, your MIL is a selfish cow, tell her she'll get a grand. 