Idk, from (my personal) experience with emotionally volitile situations, my guess would be that she is holding back because she hasnt processed it enough to bring it up (without being too mean or too kind and regretting it). She needs to work out how she feels about the situation.

It must have been something pretty bad for the negativity to outweigh all the good he did.

Either way, the info provided (or lack thereof) its not enough info to make assertions like that and, worst case, could make OP belittle her feelings by calling her out (and in the process force her to explain how she feels before she has fully processed it, which will absolutely not go well). Plus if OP brings up her lack of concearn for him that will come across as extremely narcissistic.

People need to be allowed to process traumatic situations and more often than not that means biting their tongue and not talking about the situation at all until their emotions settle down and they can think/speak rationally.

She is considering leaving OP so should get all the space she needs, instead of having her partner get it into their head that she is being selfish (its just a recipe for disaster) because of assumtions like that.

Edit: Assumptions in situations like these are almost always wrong (or at least very risky) because of incomplete data. OP needs to wait for their gf to explain how she feels, then judge from that how to proceed with said information.

She might be concearned but not able to express it because of the resentment over how OP acted.

Feelings arent so black and white that knowing something was or wasnt intentional makes them go away. My older brother has some serious mental health issues and Ive seen him have a cognitive flip and many psychotic outburts (often directed towards me), some were so severe that his pupils would dialate, and he would speak rapidfire nonsense, it was like looking at the face of the Devil. Even though he has had years of therapy and now lives on his own with his fiancee and is able to live a normal life I still struggle to look at/interact with him sometimes because I cant unsee or unfeel those things (regardless of the fact that it wasnt his fault at all). As a result I have a very awkward relationship with him to the point that our step sister says that she can feel the tension when we are in the same room together.

I feel so guilty and it isnt his fault and I do try, but I cant just forget or fully get over all that stuff no matter how much I want to. Its also not my fault.

OP's gf might be being unfair, but it's not her fault and doesnt mean she doesnt care.

Emotions often outweigh logic, even when you know you're being unfair.