You need to summon your inner resources and fight this phobia; it is all due to wrong conditioning; you can fight it by visualizing success, and telling yourself that you can do it with the help of Allah. Here, are some du'as you can repeat and affirm for empowerment.

Hasbiya Allaahu laa ilaaha illaa huwa 'alayhi tawakkalthu wahuwa rabbu al-'arshi al-azheem

(Allah is sufficient for me. There is no god beside Him. I put my trust in Him; He is the lord of the mighty throne).

This was the du'a that the believers offered when they were facing virtual massacre at the hands of the mighty army that laid siege to Madinah. However, the situation only helped to strengthen the faith and confidence of the true believers, while it broke the hearts of the feeble minded among them. The  result was they came out of the ordeal with flying colors; Allah sent down His help, and the armies were forced to flee as Allah unleashed gusty winds upon them, and they took to flight.

The above du'a has been a source of empowerment for the believers throughout history. Thanks to their faith Allah and their belief in their own ability, they have won many a battles and defeated armies many times stronger in might.  It is all yours for the taking, if only you believe in the power of Allah and your own ability with His help.

The second du'a is the du'a that Prophet Musa (peace be upon him) offered: When Allah commissioned him with the heavy responsibility of preaching to Pharaoh, he lacked the courage, and asked Allah for empowering him, and he prayed thus:

Rabbi ishrah lee sadree wa yassir lee amree wa uhlul 'uqdatan min lisaanee yafqahoo qawlee

(My Lord, expand my chest for me, and ease my task, and loosen the knot in my tongue so that they can understand my message).

You can use this du'a to seek the help of Allah.  So, I urge you to believe in the power of Allah as well as in your ability to do the job with confidence.

I pray to Allah to grant you success.