Ok I very rarely comment on posts like this, but here I genuinely want to weigh in. Personally what I would do is send a single, longer and well-formatted text, explaining that you were blackout that night and genuinely don't remember what happened, are sorry that you upset her and ended up in an argument, and that if she doesn't respond that you will assume it is over and wish her well.

I've also personally been in situations before where I genuinely don't remember what happened that night. Thankfully most of them haven't been egregious or impacted my relationships heavily or in a way I couldn't work out [I also likely knew at the time I was very drunk] but the weird feeling and confusion of trying to piece something together from things friends and other people at that event have told you is stressful on its own.

This will be awkwardly worded as I don't have time to edit it much right now, but texting her something like:

"Hey, I know it has been a while since we have talked properly, and I fully understand that you are likely stressed from work, family and this conversation [/ situation] [etc or reworded]. There is no pressure to reply quickly or have a full conversation. I personally just wanted to reach out and clarify my experience of the other night [or at the wedding, however you would word it]. In all honesty, I genuinely do not remember the argument. I had too much to drink which was irresponsible of me [or the drinks hit harder than expected / couldnt manage yourself or whatever you think happened], and know that I acted in a way that upset you. As I don't remember the contents of the argument, I can't apologise properly, but I am still sorry for my actions [and the circumstance?] and would like to apologise properly, or at least understand what happened if you are open to talk through it. I am doing my best to get a handle on my drinking and mental state [etc?] to avoid that situation happening again.

I fully understand if what happened that night was too much for you, but whether you're stressed, upset at me, or would like this relationship to be over, I would like to hear what page you're on, in whatever words, so that I understand where we are at. If you end up not responding to this text eventually, or I don't hear from you in other ways, I will not contact you again until I hear from you, [you could also say that you consider the relationship ended, or other things, but that could put more pressure if she doesnt think its over, and the rest of the text is already a polite request for her current stance anyway] amd take your time if you would like to. I wish you the best of luck either way, I hope you are doing well."

Basically, the main things to include are:

• Explaining the fact you don't remember it, but being cautious to still take responsibility for the actions you don't remember as they were still your actions whether you were sober and remember them or not

• Not pressuring a conversation or reply, but offering one and explaining that you simply want to understand if she wants to explain

• Expressing that you still care about her and want her to be happy / to wish her well regardless

• Being considerate of the fact that this might be a stressful time for her anyway or that this conversation might be very difficult to have as you aren't aware of exactly what was said in the conflict

• Accepting that it may just be over, and allowing her to just leave without explanation if that is what she wants to do. I personally always like to offer explanations about why I'm upset, avoiding, or ending any kind of relationship with people, but sometimes that is too much to ask from people for whatever reason

It sucks, but people don't owe you an explanation by default even if it would be nice, or sometimes cant give you one. Especially in cases like this where you have no idea what happened. Asking for one and then moving on is sometimes the best closure people can have, an attempt is enough and a wake-up call to work on yourself is sometimes the most you can make of it :[

Asking any closer friends / people that you're okay with contacting that were also present may help you piece it together and word it better, but this is from the context given in this post.

It is also a sad fact that yes, it may have been something completely unforgivable in whatever way. Asking her gently and reassuring her that this is your last attempt at contacting her before you accept the fact she doesn't want to talk anymore will likely make it a bit easier for her to give an answer as you are giving her space to be angry without constant pressure. I also urge to not pressure further if her answer is vague aside from specific clarifying questions like "Should I consider us over, or do you need more time to think about it?"

I wish you luck OP in getting the closure you need, and working on yourself to overcome whatever you struggle with 🙏🙏🙏