Well I suppose it is a matter of perspective - given I'm short and my high weight is in the 270's, I'd never consider 200-210 'wicked fat' on most people, though definitely heavy. If you were good friends with her and her family, likely everyone will just be happy to see you. They might notice, in a peripheral way, that you have gained weight. But nobody is going to fixate on that fact like we, ourselves, do. Don't sweat it.
I went to my brother's wedding in the mid-190's and looked gorgeous. People commented, and then the attention was on the bride and groom and I was just another joyous spectator. Dress nicely, wear your confidence like a beautiful mantle, and let the day proceed. I am sure the bride will capture all the attention and you'll just be an enhancement to her joy by showing up