It also sounds like someone has access to your apple id information. Sim cloning copies whatever information is stored to that sim card and any information that can be provided by the phone number to that sim. Accessing apps and iBooks is related not to the sim but to the device information and your account information of your apple id or iCloud id.
Here are some security tips provided by Apple:
https://support.apple.com/en-us/HT201303
I would also suggest, if you know who this person is, reporting them to your local authorities because this is considered a form of stalking and harassment.