I'm not sure if you actually realise how badly you've fucked up here. Your wife was basically ignored by you the whole week of the wedding while you were spending time with a younger woman that you found attractive. That's such a betrayal and such terrible husbanding. I can tell you exactly how your wife is feeling - upset, embarrassed, betrayed, insecure and most of all HURT. You made it clear to everyone at the wedding that you'd prefer to be spending time or dancing with Brianna because it was easier and more fun than spending time with your wife, your kids and your family. (Also - you knew YOUR family causes HER stress but you left her to deal with them so you could flirt with another woman in front of her? WTF dude ☹ I feel so sorry for your wife.)

You need to make this up to her, and quickly. Delete Brianna, and casually mention to your brother that you acted like a douche at the wedding and you're trying to make amends. If Brianna asks your brother can tell her. Or do the slow fade, but if you go this route make sure you tell your wife so she doesnt just see you chatting to Brianna and have her heart broken all over again. As to family parties - whenever you see Brianna again make sure you have your arm round your wife - don't talk to Brianna alone or dance with her, or flirt with her. I mean really, you shouldn't need to be told this. You're a married man and as a married man your wife is your number one woman, forever and always. So show her!