Having switched back to Android, it can be infuriating dealing with iPhone users. I get slammed with "messages" when someone reacts to a message and oftentimes, messages just don't show up or messages go to my iPad and not my phone. Apple makes this extremely confusing. The iPhone users never know of their message goes through or what they're actually sending to (my iCloud account or my phone number).
Sounds like you need to deactivate iMessage: https://selfsolve.apple.com/deregister-imessage/
I'm pretty excited about this development and am saddened there appears to be no way to get it immediately.