In Harry Potter and the Deathly Hallows nothing was ever mentioned about George and how he coped with his twin’s death.What happened to him after Fred's death ?
There was a 2007 Bloomsbury web chat with JK Rowling, where a similar question was asked:
The same interview confirms that his career is still in the joke shop:
I can see him continuing the joke shop as a way to continue Fred’s work (because it’s probably what they would have done together, anyway), and naming his son after a lost brother or friend is also fairly common.
In 2007, there was a documentary called JK Rowling: A Year in the Life.1 About half an hour in, she draws a family tree for the Weasleys after the books, and has this to say about George:
1 I think there’s a copy on YouTube, or alternatively it’s part of the special features on the Half-Blood Prince DVD.
George marries Angelina Johnson, Fred's old girlfriend. They have two children, Fred II, and Roxanne.
From an interview with J.K. Rowling, transcribed here:
Haven't yet found a source more reliable than the wiki for Fred marrying Angelina, I'll keep on it...
I read once that George can't make appear a Patronus anymore after his twin death.