How do I stop saying extremely hurtful things when I’m angry at my partner?

I grew up having to watch my parents cuss, blame and yell whenever they’re upset. My dad was never really present throughout my life, and has just told me that he wanted to stop talking to me. My mom has done things such as kick me out of the house, and has often used me as an outlet for her anger. I really believe that this has impacted the way I deal with situations that make me frustrated, especially the way I communicate with my partner whenever he has done something to upset me. I have said extremely hurtful things like “this is a stupid, worthless relationship” and “I hate you” and I always end up feeling extremely guilty after seeing how my words impact him. He has been incredibly patient and understanding this whole time, which makes me feel even worse as I sometimes wish that he could find someone different who treats him better (which he says he doesn’t want).

I noticed that the disrespect is often triggered whenever I feel as though I’m not enough for him. Things such as him calling another girl “insanely pretty” before we dated reminds me of everything my mom said in regards to my body, and whenever I feel as though I’m not enough, I feel the need for it to all start.

I feel manipulative whenever I apologise for saying hurtful things, because it ends up happening again. I feel such a strong wave of anger towards him that it literally controls everything I do, and I feel helpless as to how this could ever stop. I want to change, I want to be better for this relationship, and I would really appreciate your advice. How can I stop unintentionally hurting my partner whenever I feel insecure and not enough?