A:
Offering Fajr Prayer after Tayammum despite the availability of water is invalid. You have to repeat that Fajr Prayer. Also, your shyness from your friend in that situation is not the kind of praiseworthy shyness in Islam. (Part No. 4; Page No. 174) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.