TIFU by not attending my father and best friend’s wedding

Yeah. Weird. But they’ve been dating for six years now and started to when she was twenty one and he was thirty nine. He had us (my twin brother and I) when he was only a teenager, but his young age when we were born still doesn’t make the fact they’re in a relationship any less weird at times, I mean she was my literal best friend growing up, we did everything together, she swears that nothing happened between them before she was legal and that he was never a creep who made her uncomfortable or attempted to groom her, but to be honest, that doesn’t make anything about the story sound any better, it’s still an odd situation, given the fact he watched her grow up just like he did me.

I’ve been as understanding and accepting of them as I can, it’s truly wonderful to see them both happy and in love, I also think it’s enough that my brother and her family have been giving them a hard time with their disapproval, I believe that 45 and 27 isn’t all too bad to get married, they’re both grown adults so whatever. Anyways, I’m the maid of honor and I’ve been practically planning everything along her side. But when the day came along, I saw my mother and brother, both of them were extremely angry and bitter, my mother was in tears. They told me that I shouldn’t go and my mother made a decision out of it; whether I wanted to support her or them. She’s suffering from heart problems and was sick as it is, I didn’t wanna leave her alone. Her and my father were never together—as in had a legitimate relationship, but she has always loved him and claimed it’s hard for her to see him go through marrying someone our age now.

My best friend was heartbroken, crying when she called me and my father was very much displeased, she said she feels betrayed and couldn’t believe that I didn’t show up for them. The only thing that made me feel slightly better is that she has four sisters and a lot of friends as bridesmaids and guests, so it’s not like I’m one of a few who left her hanging, but I still understand her position, I would be pissed if she skipped my wedding without a reasonable excuse provided, especially if she was the maid of honor, regardless of how many others there are to substitute. In all honesty, I think I shouldn’t have blindsided her by saying I’ll come and have her fully guarantee my presence and support, only to end up not attending, but it was a last minute decision itself and I gave her a call and explained what went down with my mother, still, she’s angry and refuses to speak to me

TL:DR I didn’t go to my father and best friend’s wedding cause my mother was sick and didn’t want me to and know they’re both quite angry