First of all, at this amount, you can find some good lawyer and specialist to do it for you - mainly for tax purposes. I believe there are ways to make a clean cash-out without too much troubles if you hire good ones.

Second of all, plan your cash out: why sell everything in one shot? What will you do with fiat money? If anyway you are going to put them in bank, why not keep BTC?

Last thing, congratulations, seriously!