Is it necessary to inform the congregation when intending to end the prayer due to intrusive thoughts (waswasah) and then secretly say the takbir with the intention of concluding the prayer, knowing that informing them would cause great embarrassment and hardship?

The cure for obsessive thoughts (waswas) is to ignore them and not pay attention to them. If Satan instills the thought of interrupting your prayer, do not heed his whispers, but continue with your prayer. If you have decisively interrupted your prayer and restarted it by saying the takbirat al-ihram silently, the prayer of the congregants (ma'mumin) does not become invalid due to this according to many scholars. This is because they said the takbirat al-ihram behind you, and your interruption of the prayer is a hidden matter unknown to them. Therefore, their prayer is judged as valid. Consequently, you are not required to inform the congregants of what happened. You must strive against these obsessive thoughts and not pay attention to them. Your adherence to the Hanbali school of thought does not prevent you from following another madhhab when there is a need, especially since you are afflicted with waswas. One suffering from waswas is permitted to adopt the easiest opinions.