When is it OK to lie? If the truth will really hurt should you say it anyway?

It is never ok to lie.  We must be honesty and leave the result to G-d.

In general when you lie ... you don’t lie the other ... you lie yourself.

And on a short period of time that is not good for you.

To lie is a subjective thing. Is anything 100% certain and true in this world?

It’s never ok to lie ... in my opinion

What if an ugly alien comes to you and says: If you human consider me beautiful I’ll give you a cure to all mankind illnesses, otherwise all bring some new viruses t Earth. What would you tell him?

How about:
I’ll lie to tell you “.... “ but now I said it.

I think you should avoid this topic as much as possible. ( lying )