Windows Vista, iTunes 12.1.2.27, iOS9 on iPhone 6.
I have Windows Vista with iTunes 12.1.2.27 and just installed iOS9 on my iPhone 6. Now when I try to connect a message states the iPhone cannot be used because it requires a newer version of iTunes. I connected to www.itunes.com and cannot install the iTunes 12.3 with my operating system. I would like to revert to the iOS8.4 and the backup that I made immediately prior to installing the new iOS. Thanks for any ideas to get me out of this mess.
iPhone 6, iOS 9