I can’t own up to anything

My relationship with my partner if 5 years is about to fail because I can never own up to my mistakes. Everything is always someone else’s fault to me, I can never take accountability. I will even tell white lies to get out of taking accountability for things. Both of my parents are the same way, I know it stems from childhood and all that yada yada. I just need to stop and “put on my big girl pants” and own up to shit. Something wasn’t done? Well I just need to say that I didn’t do it, not “well I didn’t do it because xyz” no I just didn’t do it.

My body rejects telling the truth and owning up to things so hard. I am currently coming down with some kind of flu after a rough few days of arguments with my partner over this issue.

I don’t want to lose this life we have together, I really hate myself so much for this.