I'd tell my immediate family. If it was MY ticket that is. I would tell my mum, my dad, my brother - thats it.
There are specific family members on my side I wouldn't want to have that information, so i'd not tell anyone.
I think then if anyone commented on our improved lifestyle, like a friend, I'd be happy to lie and tell them DP has gotten a new job or something. I mean, it would be true, he wouldn't stay in the job he's in that he hates if we had won lotto, he's looking for a new job as it is, so I would... errrm... tell them a misleading, but true, fact
As for my inlaws...
I dunno, honestly, I'd tell DP he absolutely cannot tell his family about the winning. He's welcome to help his parents buy a house, and tell them that we'd made a good investment (not a complete lie, invested in a ticket
But I wouldn't want it to change anything.
I'd want it to not be a big deal.
I'd want it to make our lives easier and not risk it changing how people veiw us...I'd hate to have family and friends look at us with $$$ in their eyes.