What should I do and how can I repent from showing off (riyaa') after talking to my family members about my repentance and deeds performed to draw closer to Allah, with the intention of gaining their admiration?

The door of repentance is open. If you realize the ugliness of your deed, then abandon it, resolve never to repeat it, and regret what you have done. If you repent with sincere repentance that fulfills its conditions, then Allah will accept your repentance, the effect of the sin will be removed from you, and you will be as if you had not sinned; for the Prophet, peace and blessings be upon him, said: "The one who repents from sin is like one who has no sin." And be diligent in sincerity in your actions and avoid showing off.