Are you getting her a new friend to keep her company? If so, she will be pretty lonely outside on her own, so I would suggest keeping her in until you get her a new husbun. If not, I would seriously consider getting her a new friend. The only way I have/would keep a single rabbit is inside so they get plenty of company and keeping rabbits singly isn't something I would do unless for some reason necessary.
Noserubs to Coco, she is grieving for Rocky just like you are.