I'm sorry you've been through this. My childhood was violent, I was made to think it was all my imagination when I inevitably had a breakdown at aged 16, I was on Prozac for a decade, then tried counselling. Didn't click with first counsellor, so I found another and although I saw her for a year or so, I would say it went a long way to make me better and off medication. (Not that medication is a bad thing at all).
Things I learned that helped me:
You can't do anything about the past, but you can do something about the now and your future. I could have let my abuse swallow up more decades of my life, or I could stick my two fingers up at my past and start to work on me and my self esteem and become happy and successful.
Surround yourself with good people. It sounds obvious, but honestly, I love my friends more than some of my family. My friends are my real family. After a childhood of being treated like shit and being told you're shit, you believe it. So cut people that bring you down out of your life and surround yourself with people who lift you up. Honestly, I think your partner sounds like he isn't a person who deserves you in his life.
Acknowledge your successes. What you have achieved in life is DESPITE of your difficult start to life, which shows resilience, bravery and strength. Give yourself kudos for that.
Recognise behaviour patterns. I live my life very differently to my mum, I wasn't going to go down that same path. I now find I get a good measure of people and if I see behaviours that I recognise as unhealthy, I back off from those people.
Remember none of what happened to you was your fault. I was told I was a bitch as a girl and deserved it. Yep, deserved my 16st 6ft stepdad beating the crap out of my tiny 8 year old frame. I don't care if I was The Omen, I now realise I was a child and I am not to blame.
Take time to be thankful for what you have and not on what you didn't have or don't have. But if there's things you want that is achievable and it will help you be happy, then go for it.
Keep talking to loved ones and a counsellor. You eventually feel like you've got it all out and it feels much less significant and no longer casts a shadow.
Finally, don't beat yourself up for feeling like you do. It takes time to heal.
Good luck.