You can restore your original mount_ntfs (A) or you can delete that "w" inside the new file (B).

A- sudo rm /sbin/mount_ntfs
sudo mv /sbin/mount_ntfs.orig /sbin/mount_ntfs

B- sudo nano /sbin/mount_ntfs

Replace this line:
/sbin/mount_ntfs.orig -o rw "$@"
With this one:
/sbin/mount_ntfs.orig -o r "$@"

Then exit nano, save, repair permissions and reboot.

Just a guess, I don't know if it's gonna work.

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