o7
Then you need to practice more and get your mind straight.
When you practice you think of your family, kids, partner, mom, dad dogs or cats or any pet.
Think of them being attacked and they will die unless you shoot them. Practice shooting them in your mind,
If you are ever in a situation where you do need to shoot a human, you will at least have it in your mind that you can indeed save yourself or whatever you love, from being harmed.
Cops will never be there in time to save your sorry ass.
To say you don't know if you could, already makes you a victim. Quit thinking like that. Know that you could.