You need to make friends with his friends.
Contact them directly. They do not know you. So make the overtures. They were there first - this does not make them right-er or better. It just makes them first-er.
Here's a script (phone or email) -
It's me, Margie, Bill's wife. How are you and Susan and the kids? I wanted to extend an invitation to you to come over in August. And if Samantha wants to come on her own, that would be great, too. See you soon.
Essentially, you need to demonstrate your generosity, because right now it does not look that way to your husband's pals.
If they have any brains at all, they will see how you are living, and will understand that your husband can't just drop everything and go to Aruba for the weekend anymore, too.