Im so sorry you had a difficult, toxic relationship with your mother. I know this may be upsetting for you but it would be quite difficult to get anything changed unless it is factually incorrect. If the records note you were upset or angry, thats not actually inaccurate, just information is not there to explain why you were upset and angry.
This link explains the law around medical records and what you might be able to achieve.
https://ico.org.uk/for-the-public/your-right-to-get-your-data-corrected/
I have attempted to get a medical record changed (not mine), to help a friend. I managed to get a supplementary statement added to the record, but it took around 18 months. The barriers put up...... To be frank, the drain on energy and the fight, well, i dont think it is worth the aggravation. It was a disillusioning experience and I wasnt even the person directly affected. I contacted the ICO several times to complain. A change is supposed to be done in one month, or at most three, but if there was a chance the Trust would do it, albeit 6 or 14 months late, the ICO preferred to give the Trust the opportunity to correct themselves, rather than give them an enforcement notice or penalty. So there was no accountability or consequence for failure to comply with the timeframe.....
Remember that you know the truth of the situation between you and your mum and how you felt and why you felt that way. Your feelings were and still are real and valid.
If you can, i think it would be really helpful for you to speak to a therapist about what youve been through to help you process the suffering and allow you to heal and have more peace. It honestly really helps.