Abusers crawl inside your head and plant weeds there that whisper their world view into your own thoughts. If you think of your mind like a garden that you want to cultivate. Then already recognising that there are weeds there is you taking back power by just noticing these whispering weeds. That they are not part of your garden. What you need to get help with is how to either pull these weeds or find enough weed killer to spray them into being more silent and less intrusive. That though is a personal journey. I took mine and had a good therapist that armed me with what I needed. Therapist specifically trained to help people who have come from abused backgrounds are your best bet. What you are is a survivor.
It is hard though because at points you have to actively observe the horrible things the weeds say and revisit where it comes from and the toxic soil it sprung from. But then you have to challenge it. Abusers are good at twisting you against yourself making out it is you in the wrong. All the badness is your fault. But they are liars, power trippers and don't value you in any meaningful way if they are tearing you down.
So like my stepfather would always call me useless and worthless and other less savoury things. To challenge that I argue back at it. I can't be that useless if people come to me looking for pragmatic advice, or call me up when they are hurting. I can't be worthless if people care enough about my well being and make efforts to help me during the bad times. So it is like looking at what is true in your life to counteract the lies you have been told. A good therapist will help you refine this process.
You can also potentially help yourself with the negative chatter with this book.
Taming Your Gremlin (Revised Edition): A Surprisingly Simple Method for Getting Out of Your Own Way - Kindle edition by David Carson, Richard. Self-Help Kindle eBooks @ Amazon.com.
It is a book I often recommend just because it helped me get over the initial hurdle of getting help. Because if you feel you deserve pain and suffering then there is part of you that also feels you don't deserve help because that would end that pain and suffering which you apparently deserve... There is a self saboteur that can live within us and undermine our attempts at escaping misery. Maybe you even think there are others more worthy than you?
That is not true though you have every right to happiness and the life you want. I hope you can begin pulling your whispering weeds. I have managed to kill most of mine but they sometimes still whisper but it does not dominate my life so much. I also have some weedkiller to spray them with. Cultivate your mental garden, get someone to help you identify and pull weeds. Learn to enrich your soil by simply being good to yourself. You can silence these weeds, you can become more than the scum out there have made you. You coming on here is proof of that already.
Take care.