"I informed my late husband that once we had our child he was in second place and all my life was centred around DD" Unbelievable! You are winding us up I assume.
Because a man might like a bit of attention, as indeed we all do, does not mean he is a "spoilt brat."
Partners need to nurture their relationship in order to provide a stable background for their children; and it is good for children to learn that they cannot always come first.
Your DGD will be with someone she knows well, she will be thoroughly spoiled and will love every minute of it. In the meantime your daughter and her partner will have some precious time together. What's not to like, as they say?