In such a situation, the best course of action would be to remove her power or ability to act, not potentially aggravate her further.

Claiming she can do nothing to you is blind and arrogant. People can always find ways to hurt people; especially when they have power, especially when they're mentally unstable. If being dead makes you as functionally immortal as she is, could she not simply bring the same trick down upon you? If she's as powerful as you describe, she could easily do worse. Or the same to those you care about. Or the same to anyone in the general vicinity who happened to be in the wrong place.

If you are serious about this, this is not the time for underestimation.