All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
This length that nullifies Al-Fatihah and prevents continuity [in reciting it] depends on the custom. The short pause like the aforementioned seconds, and even what is more than that, does not harm.
Moreover, a long interruption in other than Al-Fatihah and the Tashahhud does not harm, as stated by the jurists.
Ash-Sherbeeni said:
“Its issue – meaning the statement of An-Nawawi in al-Minhaaj – is that continuity is not a condition – i.e. in Tashahhud – but the most preponderant opinion is that it is an obligation as in at-Tatimah. Ibn ar-Rif’ah said: ‘It is by analogy to what has already been discussed about Al-Fatihah.” [End of quote]
You have to repel these whispers, not pay any attention to them, and not give in to them, for giving in to them will lead you to a great evil.
Allah knows best.