Karlach is an origin character that can only be saved if you pick her. Even so, there is nothing wrong with dropping the game and coming back when you feel like you're ready
In regards to that first statement:
I could be wrong, but I believe there is a slight bit of misinformation here in that Karlach cannot be "saved" outside of the two options where she survives even if chosen as an origin character; her endings where she is saved are still the same as when she is present only as a companion.
