How do I prevent my protagonist from ending the world?

Question

My protagonist is an immortal person that’s powerful enough to end all with but a thought. She has amnesia due to overusing her power when she recreated the world.

The amnesia part is very important as she doesn’t remember the discrimination she faced in her life, all the bad she suffered, as she didn’t have anything good happen to her in her life except one thing: Her pet (the narrator) who she also doesn’t remember.

Due to the amnesia she doesn’t know how powerful she is, or that she is immortal. But over time her memories come back and with them her knowledge of her powers and here lies the problem:

With only the bad memories, how do I prevent her from going nuclear when her first and most important friend in the story gets killed by seemingly random bandits?

Do I dial down how much she remembers of her powers up to that point, or do I put her inner conflict right at that moment when her friend dies because he was such a kind person? (I don’t quite like the second one, but I might be off and that’s exactly the answer to my question.)

Character: As a character with amnesia she adopts much of the behavior of the people around her. The very first person she meets after waking up and walking for days without food/water or seeing anyone is her kind hearted soon to be friend. She is a curious person and likes to learn a lot.

While her friend knows a lot and likes to teach. He also wants to help her regain her memories. She remembers bits and pieces but nothing traumatizing. The first event that unravels one of the traumatizing memories is when she and her friend are robbed, there she remembers her parents (elves) being captured and enslaved by bandits when she was still a child. These little bits of past time memories are triggered by some significant and some benign events until a group of people attacks my protagonist and her friend gets killed in the process, my protagonist would’ve died too, were she able to die.

In the former world she was a person, who did what she thought right when she never had anyone to teach her what’s right. And now she had a teacher and friend brutally murdered in front of her.

Edit:

1. She acquired her powers later on
2. When she had enough she destroyed and rebuilt the world from scratch
3. She destroyed it because she could only see the bad everywhere she looked (she was omniscient at some point but gave that power to the narrator very quickly because it didn’t support her worldview of everything being bad)
4. And she recreated it because she believed she would make it the perfect world
5. She learns right from wrong from her friend while having amnesia but she didn’t have a moral compass before her amnesia
6. She didn’t create the world where all the bad forgotten memories stem from, she however create the world where her friend dies

Answer 1

If she is a bit of a tabula rasa when she meets the kind friend, that might seem odd as you suggest she has forgotten herself. Losing memories is one thing, but your complete identity and sense of self? So be it.

A goddess (destroyers of worlds tend to be at least minor deities) with no memory of aught but misery and watching her only friend dying will certainly be in a dangerous mood.

Hitting the reset button, so to speak, drained her of everything so there could be a deep seated reluctance to do it again - she does not understand why as she has forgotten the previous reset.

Her friend - probably the first in eons - is dead. Her wrath builds and the energy crackles, but this is George’s world - destroying it essentially kills him again.

Her grief and rage can be held in check by her love of him, her sorrow that he is dead but not destroyed. She might even intuit that destroying the world will wipe her memory of him and it will be as though he had never existed. George deserves better than that, better than utter destruction and annihilation.

Answer 2

A few suggestions on stopping the destruction of the world:

1. She hasn't regained her full power (or knowledge of how to use that power) - she only destroys one forest/town/house. This could then allow you to explore the emotions she feels, as a character, using her power to kill/destroy innocents, or the reactions the people around her.
2. She can destroy the world but she is knocked out and drugged by the bandits before she can react because she is no used to using her power.
3. Her power is limited by her knowledge of its abilities - and she doesn't remember destroying the world.
4. However she gained the power - someone else also gained the power, and they stopped her from using it to destroy the world.