Compound objects & complements

When we have two or more subject complements or direct objects, for example, that are not two separate things or ideas, but instead one idea expressed in different ways, how should we punctuate, construct these ideas? Here are some examples I made up: (I tried to create sentences where a conjunction like 'and' just doesn't seem valid)

The supporters have been anything but encouraging, quite the opposite.

The supporters have been anything but encouraging--quite the opposite.

The supporters have been anything but encouraging. They have been quite the opposite.

I don't want them to know that my injury has affected me, that I haven't slept in three days.

I don't want them to know that my injury has affected me--that I haven't slept in three days.

I don't want them to know that my injury has affected me. I don't want them to know that I haven't slept in three days.

Incidentally, what is the word for two things that cannot exist together at the same time/co-exist. Has slipped my mind.

Thank you