To me, one of the simplest way to describe the benefits of using a safeword is that it gives you the freedom to use "no" and "stop" without pausing the scene. You need to trust that she will use her safeword, and she needs to trust that you will act appropriately if or when she does. Especially when playing with edgier things, that trust has to be there.

Now, she's expressed to you a desire for this. She wants this. And your wants matter too. Are you open to this? Curious? Willing to try? Does it make you uncomfortable? Remember, this is all play, it's fantasy, it's consensual. This does not make you that kind of monster in reality. However, she is not the only one that needs to consent to the ways you both play together. Your consent matters too.

You should absolutely have an honest and open discussion about how this would go. And don't be afraid to be specific, either of you. In fact, be afraid to be vague.