If what you saying is the truth, then you will have been in a very good profit already, so if you want to sell, then it’s your choice, but if you are disturbed because of what your siblings are saying, then I will say your story is fake.
It's a full blown lie, a false alarm, crooked story and not really worth any advise.
OP didn't mention about recovering his wallet that means he watched his investment grow and through out those period of holding and waiting, nothing pops to his brain on what to do with the profits.
Even a billionaire investor won't seek help from a forum on how to spend $1.8M BTC. In my observation, OP don't own any Bitcoin.