First Preorder Sale Disaster

Okay so I ordered 5 books from Amazon for about $30 each, and I had confirmed delivery for between January 1st and January 7th (today). I made a presale listing on ebay, and they all sold for about $80. I clearly stated my expected date that I will have them in hand, as well as made it clear it was a preorder. Now the day has come and I received an email from amazon saying my order is delayed and does not yet have a new delivery date. I do not want to cancel all five orders as I know this will significantly affect my seller status, but I also can’t just wait for the item if I dont know when it will be in. Should I just explain the situation to my buyers and ask them to cancel, aplogize, and maybe offer a discount or even send them the book for free when I do receive it? Regardless, this was my first and last presale listing on eBay - so be cautious out there. Any help with this would be appreciated.