@xraydave
Hey there. I have been very open about the fact that I have been where you are now. When I was at my worst, a few years ago, I behaved horribly, most of all to my partner. Low empathy and high aggression. For me it was PTSD that was at that point unknown to me, an alcohol issue, an unmedicated hormone problem, generel immaturity but, and I think that is important, most of all it was a great deal of confusion and misunderstood pain.
None of my (sometimes very bad) behavior came from a wish to be bad or do bad. I just did not know any better. Luckily, when I got better my partner had it in him to forgive me for everything. Like you I come from a severely narcissistic family, and for a time I was afraid I was one of them. I was not.
But I was very immature. I think everybody raised by narcissists faces this issue to some degree. I had to teach myself how to be calm and understanding, first to myself and then to others. When one lives a lifetime of being told one is wrong, stupid or hysterical by cruel narcissist it will take some time and learning and growing up, and a lot of mistakes, to learn another way. Empathy is a skill that needs to be developed. Staying calm, expressing oneself clearly in times of emotional turmoil, treating others better then oneself has been treated, all of this takes a great deal of learning and catching up.
You are very young. It doesn't seem that way with 20, but you are. You have only just entered the phase of your life where you can take controll of your self. It's only just starting.
You want to realize that you are handicapped. You have to deal with underdeveloped emotional growth, because you were not provided what young people need to have provided: A upbringing that prepares them for navigating the deep sea of human interaction and connection.
This is something that can be overcome.
Some people say that if brute force is not working, one is simply not using enough. I never found that to be true. Brute force is the one thing we learn from a narcissistic upbringing, and this is a problem where that approach fails. This is a problem of patience and understanding. Its about listening not shouting. First to yourself, and only then can you extend it to others. You seem to be making good progress already. Good luck on your journey, mate.