I'm sorry. I understand how it feels to have a parent who doesn't care. IME, they react this way because they don't have compassion or empathy for us. Narcissists only care about what happens *to them*, so if the abuse didn't happen to your mom she wouldn't care about it.
I dealt with my father's narcissism by learning that he really can't feel anything for me, so I have to stop expecting anything from him. Once I realized that, I started to heal. I don't talk to him anymore. If you're not in therapy, I recommend seeing a therapist who specializes in parental emotional neglect and narcissistic parents. On Youtube, check out Dr. Ramani Durvasula. She talks a lot about narcissism and the way it affects a person.
I truly hope you heal and find better people to love you.
You deserve a lot better than this, just remember that.