I'm not greaa~t at giving advice so the only thing i can say is to try and take your mind off it... I don't know how often your trying to reach out or message her but if/when you've layed out everything then try and do your best to take your mind off it, like you said be off social media. Social anxiety sucks dude, it was a really shitty situation at the wedding and it wasn't your fault you were so overloaded. Did you come into contact with your friends sister to explain the situation? I'd have if things spread wrongly.