Good for you. That was the right decision. I doubt you will EVER regret it but I'll bet you would have if you didn't go.
I miss Florida right now. I'll be back in about 6 weeks. Travel can do wonders for you - even if it's a short time. Change of venue. A distraction.
Go through your closet and try on possible dresses. Choose one that flatters you the most and makes you feel comfortable. Splurge for a new lipstick - use foundation and a blush if you look tired. Fix your hair special. If you go the extra mile (at little or no cost) - you will be amazed how much better you will feel about yourself.
Now - leave your worries on your doorstep. You can make a promise to yourself that you're going there to enjoy the wedding, wish the bride and groom well and just have a good time with your relatives. I will bet they'd be happier not talking about your troubles either. And if they ask - just tell them you're "moving forward" and "optimistic" that things are going to get better.
Trust me on this, Mish - it is the way to go.
August is still a way's off. You might be able to make further cuts on a few things and make that work too. But for now - concentrate on having a good time. 5 hours is not that far.
