Yes, please do not release her! The odds are that she would die a cruel death! While some colonies of feral rabbits can be found, it is rare for them to successfully establish themselves in the wild. First, they have been domesticated for 100's of years and have lost many of their natural instincts for survival. Secondly, they will worsen the spread of disease among the wild population. Thirdly, they can not successfully reproduce with North American rabbits or hares. Domestic rabbits evolved in Europe and North Africa. They have a different number of chromosomes. Fourthly, because of the stated reasons, it is illegal to realease domestic rabbits into the wild. I have seen, small colonies, surviving in remote areas. They are the descendents of rabbits released by farmers who went out of business. These colonies eventually die out, due to inbreeding. The only long term colonies, that I am aware of, are located on islands. That is because of a lack of predators and/or competition from other lagomorphs.
I would not recommend selling her, unless the new owner was made fully aware of her problem. It's a matter of ethicacy. I'd use her to feed my family. That way, she does not suffer and I have gotten part or all of my money back, by way of not having to buy meat for that meal.
I hope she does better next time and provides you with lots of healthy kits.
Mike