Ok. This may be long and I have name changed as there's some fairly personal stuff in this.
I completely get it @MyFastZebra. I grew up like you, horrendous parents; abject poverty (eating dry bread and sitting in a house with no electricity as we'd been cut off, clean clothes were a wish!), my dad was violent, mean and aggressive. My mum suffered but threw me under the bus to save herself, we had golden child and scapegoat dynamic between me and my brother and he was the golden boy who could do no wrong. I was told every single day I was stupid; thick and useless. My dad was a classic narc.
a teacher lied for me on my school report, because in his words, he knew what my dad would do to me if he told the truth about me messing in class. I also suffered CSA from my uncle. On top of all that I was an easy target for bullies too.
It absolutely destroys something fundamental in you when even your parents cant love you. You feel so alone and unlovable and become "old for your years" as there is no other choice.
That said, I'm a year older than you now, and I enjoy my life, it's taken a long time to get there, some serious work along the way, a chunk of reinventing myself and avoiding some triggers too. (I cannot watch Disney's inside out at all, reduces me to a sobbing mess, the part where it talks about core happy memories and they're being banked, I realised I had less than 5 in my whole life up to 16 years old!).
I married a much milder version of my dad (just the angry shouty part) of a guy who showed me attention and had a wonderful child. Realised when they were 4 years old this wasn't what I wanted for them and went to counselling for that. I've realised focus on fixing the immediate thing that needs fixing, you'll never heal the old stuff fully so unless it impacts right now, a box is perfectly ok to stick it in.
Take the small wins; you are absolutely not weak. If you were you wouldn't be standing solid right now, your foundations may wobble occasionally but they're there and you built them. That makes you incredible. Most people have others building their foundations and you created your own from chaos.
So right now you have an issue with some awful bullies at work. Work on fixing that. Is it self confidence, are there any books that can help on that. Can you get support on that from a union at work to address the issues. Look at another job etc.
start thinking "fuck you" at them every time they're mean and hold your head high. Anything that changes a little bit how you feel will all help.
When my child hit preteens I realised I was being shouty and aggressive at times. I can't fix my childhood, but I did take myself off for some epic (and blooming expensive) parenting classes from someone who specialised in helping parents when they came from a tough background. I worked on that and completely changed the outlook of our house by doing that work. It doesn't fix the underlying issue I had, but I can work on the here and now and know I can be better. I just sometimes need help to get there.
Can you help others who grew up in your situation, I volunteer for a charity that provides beds to children who don't have them. It's my little bit of paying it forward to acknowledge it's still there for a lot of people and if I can help make someone's life easier then that all helps them in future.
Only you can decide how to move forward. It's fine to sit and cry at the unfairness of it all, because it is unfair, but if you only sit and cry you never find the small glimmers in life. You've got your own place, you can have a coffee in your own place and know you're safe, because that's your peace.
You're strong and kickass, with a few wobbles. Look for the glimmers. 