I am just wondering if they need to give me back all that money, or do they just "throw the swithch" back on for my insurance, or if I have a say in the matter.
They have to do one or the other. It is not your choice which. It may not be their choice which. It's unlikely, though not impossible, that the insurance carrier will accept you retroactively all the way to January. But a lot will depend on how it came about. Did you slip through the cracks and it was an honest administrative error? Or was it a calculated risk on the part of the employer? It makes a difference sometimes.