I'd consult with a good attorney and a good accountant. I'd build a house on one of my parents' spare lots and hire a housekeeper (hopefully my cousin) for my parents. Buy their remaining property and house from them, give them life tenancy, and figure out how to set up a trust so that my mom could go into a home if need be. And, I'd pay the tuition for a friend's daughter to go to vet school.
Then, I'd donate money to charity, and keep doing what I do for a living because I like what I do. And, I'd play "Secret Santa" and give money to people who are facing really difficult times. My DH would have a lot of other ideas, but if it were MY money...I'd probably buy him a new truck just to shut him up. And, I'd probably buy a place on Lake of the Woods and go work there from May until September. That would be for me. LoW is my familiar.