Wedding guest outfit.

Please help me! My brother in law is getting married this Saturday, this is the second dress that I have that is good enough for a wedding, the other one is lace black dress. I still have this week to buy a dress. What do you think about this one as first option?. My husband's cousin is getting married in September 2, so I can't really use the same dress for two weddings. Any ideas about what to wear on top to hide my shoulders? or without anything? Thanks!