It doesn’t belong to you, personally

When those you love become lost, their behavior is not who they are.  If they become enveloped in darkness, they may not be able to produce anything but darkness.  They may try to draw you into it, using your love as the tether.  They may direct life-or-death, world-ending statements at you, because their pain makes them believe their very life is at stake.  Until they deal with their own pain, negativity will exude from them in all directions.  See it for what it is, an outward expression of pain.  It doesn’t belong to you, personally.