I really do not understand your percieved predicament. Allow me to explain my position so maybe you can correct my own failures in understanding your post.
I have had a pretty emotionally abusive friendship with a girl I met about three years ago that mainly consisted of getting drunk together.
Sounds like a quality relationship...but you are acknowledging the abuse of the interactions, I get that. So you ended it right?
A year and a half ago I moved away and we barely kept in touch.
Ahh, good. Abusive relationship, you didn't formally end it BUT you got yourself out of the immediate 'danger' of the situation. Good call. Out of sight, out of mind...and in this case, def should work.
For financial reasons and an overwhelming sense of empathy towards the whole wedding, I wanted to back out.
Bride/friend was/is abusive to you. You moved. You did not stay in contact despite the social interactive engagement you told the Bride/friend you would attend prior to your departure. I mean, given your background info, I can give you the benefit of the doubt that you may have felt pressured/guilt-tripped/coerced into attending...esp considering you were in the same town/area.
I decided not to burn my bridges with her but explained my financial and emotional strains with everything that was going on. I apologized and hoped she would understand.
This is where you start to lose me. Why do you care? You had/have an 'out'. She was abusive to you, you both were clearly not in contact with one another let alone acting as 'friends', but you still seek her approval of not attending a function that does not even remotely interest or even apply to you anymore?
No one is going to care if we're not there, but people are not going to be happy to see us if we are. I totally agree with him but at the time I felt caught between a rock and a hard place.
Your BF seems to be applying logic to this situation. Correctly, I might add. You acknowledge he is correct, but you are still stressed over someone you don't see anymore, have no contact with, and generally have no interest with beyond drinking. I do not see this 'rock and a hard place' that you are referring to. You owe this bridge nothing, let alone any explanations to Katy or the MOH. As you said:
The MOH sent me a couple of passive aggressive facebook messages and subtweets but who cares
If no one cares, why are you posting this and getting stressed? Moreover, why do you proceed to write out 4x paragraphs about interaction on the very social medium you stated was not a big deal to you?
Anyway, I just don't know why she was ever talking to me AT ALL after I backed out of the wedding, I don't know her, we're not friends. LEAVE ME ALONE.
Umm...so block/unfriend her on your social media accounts and phone contacts. You are in an entirely different area code (assuming) what exactly does this wedding party hold over you to compel you to feel obligated to either explain your behavior or even attend in the first place? I simply am not tracking your behavior/responses... You want to be left alone and are in a completely different area and the only way these people are bothering you is via online/telephonic communications - both mediums of which are very amiable to blocking unwanted contacts.
After all of this, I have decided I absolutely have no business attending that wedding. I know a lot of this is on me. I was a shitty friend to Sara to back out at the last minute like that. I bailed and I could have been a hell of a lot nicer and done things way differently. I should have backed out when I moved because I never intended to keep in touch.
Finally something I get. And something that actually seems honest. You straight up say:
I never intended to keep in touch.
Cripes man, seriously?!? What is the problem here? You don't want to be friends with her. Don't live near her. Are not involved directly in the wedding party. You don't speak with her or generallly interact with her. And, cherry on top, you admit you do not even want to be friends with her or her cohorts.
I'm going to send an overpriced wedding gift and a letter apologizing for being a shitty friend. Then, I am probably never going to hear from any of these people ever again.
Dafuq for? Why do you 'owe' this woman anything? You don't want to go to the wedding, you are not interested in her nuptials, and you really straight do not like the woman at all. Sooo, why the hell are you going to buy her an expensive gift?
For financial reasons and an overwhelming sense of empathy towards the whole wedding...
Seriously, you cite money as a reason and then will buy her an expensive gift? Wtf?
And you are going to apologize to her no less? Dude...so weak, so very very weak.
You don't want any part of these people in your life, you don't see any of them, you don't interact with them (in RL), so why can't you simply unfriend them and ignore them?
You are not obligated for any reason and if anything, apologizing and providing a gift, completely undermines your comment that the relationship was toxic in the first place.
I guess, in summation, Zoolander said it best...
TLDR: Cut off all contact with the woman, and her crew, that you no longer want to be a part of. The only part I truly think you understand is this:
I know a lot of this is on me
B/c it is...rip the mother fucking bandaid off, yo.
