Hello Giselle, Welcome!
I know what you mean about a bpd mother. I have a mother with bpd who was diagnosed over five years ago but has had it ever since I can remember.
Am not sure whether your mother lives with you. I lived with her as a minor until I was 18 and for 3 years on a part-time basis as a care giver in my 50s. I developed severe depression and agoraphobia when I was a caregiver. I will not do that ever again.
I am able to spend a few hours a week with her by doing the gray rock method of not telling her anything about myself. (Gray rock means to be as interesting and engaging as a rock.) She alternates between telling me pity stories (exaggerating physical symptoms) or is passive aggressive bordering on rude. I answer oh, I'm sorry or that's too bad mostly. She really wants me to do something for her or goad me into a fight.
She has an abnormal fear of abandonment. I couldn't go out for a quick coffee when I was caregiving without her yelling and being angry. She pulls similar behavior with FOO members.
I feel sorry for her and love her. I believe she was born with a brain abnormality which causes BPD acting out. She refuses therapy and sees no problem acting like a bully. I can tell she enjoys that behavior.
I played the role of parent to her growing up and was conditioned to take care of her emotional needs. That kind of childhood grooms you to act out of Fear, Obligation and Guilt (FOG). You say you feel guilty which may stem from similar childhood experiences as mine.
It helps me to repeat the three C's when I feel the FOG coming on: I didn't Cause it, I can't Cure it and I can't Control it.
Am really sorry she disrupted your wedding day and the stress is causing you physical symptoms. Those are common themes for those of us with BPD mothers.