iBooks for iMac won't open old books

Until recently I could read all my books I had in iBooks on my iMac. But now, when I try an open an older book, which I purchased with my OLD Apple ID ( which I found out now it no longer exists, since Apple doesn't like people with more than one Apple ID. I had to change it because it used my old DEAD email address, so I changed it to my current email address) . Everything was fine until recently. Now, for some stupid reason iBooks requires Apple ID verification on old purchases which used my OLD Apple ID, before I can open it up. The file is not on iCloud it is on My Computer, but it won't open any one of them. I have about 20 books purchased with my OLD Apple ID. When I try and log onto my OLD Apple ID I get a message from Apple that it no longer exists. Therefore I am in a "Catch 22": I can't open any OLD books in iBooks, because it needs verification from my OLD Apple ID, but it now doesn't exist and I can't make another Apple ID with the same name, since I already have one, and I can't delete my Current Apple ID, since that would really open up a "Can of Worms". HELP!! IS THERE ANY WAY TO WORK AROUND THIS STUPID PROBLEM!!!!