Hire a lawyer and an accountant immediately. Take every feasible legal precaution to shield my identity.

If the identity shield is doable, disclose the truth to no one. Pretend I've gotten a modest inheritance. Keep driving the same car.

Over the next few years, pretend to be lucky at investments. Take a few more vacations but be low key about it. Buy a piece of land and build a custom house. Fortunately my tastes are more quirky than ostentatious.

If the identity shield is not doable then wait. Take the time to set up certain arrangements, then claim the prize on a busy news week or on a Friday afternoon before a holiday weekend. Then change my name immediately, leave the country, and ghost everybody.