Does Not Equal
With good boundaries, empathy does not equal impact.
You can feel that the other feels what they feel without taking it on or engaging in storytelling about it. You can simply feel what you feel without workshopping the feelings, or even identifying them.
All you need to know, (and this is the boundary part,) is "here is what is MINE, there that is, NOT MINE."
The boundary is the distinction. See the distinction, HAVE the boundary.