You use realistically when you want to emphasize that what you are saying is true, even though you would prefer it not to be true.
unrealistically
Realistically, there is never one right answer.
实际上,从来没有一个正确的答案。
As an adult, you can assess the situation realistically.
作为成年人,你可以对情况作出现实的评估。
What results can you realistically expect?
实事求是地说,你还能期望什么结果?
the definition of what is realistically possible.
现实可能性的定义。