ExoticFlower, as you learn that you are capable of protecting yourself from further abuse the fear does dissipate. Your mother has a gun?! And is capable of using it on you?! OMG! As you learn to literally and physically protect yourself from her, without feeling guilty for doing so, you will feel stronger. OMG, I cannot even begin to imagine what a childhood you've had with her! And you came out of it alive! You owe it to yourself to continue to keep youself safe from harm.
I have slowly over the course of years of therapy stopped having this paralyzing fear of my physically abusive parents. I still fear I'll be physically assaulted by any adult who lets his/her anger be shown. Transference, yeah. But thankfully my parents have put the belt away and they've been real nice to me, except for their occasional anger at choices I've made for myself, such as divorcing my ex. I keep the necessary distance from them, I take whatever goodness does come my way. But they don't have a gun, they've even put the belt away, not that I'd ever compare those two instruments!
It must be tough for you, having the abuse weapon alive and well....
Take good care of yourself, protect yourself good!
All the best,
9874