Is your Mum still alive? Can you talk to her about it now. If you could talk to her about the way it made you feel then maybe some healing could start with the wound that is still very toxic and doing you so much damage.

If she is not around anymore maybe you could write her a letter expressing all the emotions you felt then and now. You could then tear the letter up or burn it as a means of letting it go. You need relief from this anger that must be very draining on your emotions.