What should I do if I lose my temper after drinking and scold my family members? I regret it.

Stand low. A sincere apology. Admit that you drank too much and didn't behave properly, and your gibberish was not controlled by your brain. After you sobered up, your family told you the process and they realized that you had gone drunk and made a mistake and hurt your cousin. Now you regret it very much. Please forgive me, cousin. Ask him to come back as soon as possible or go to him to resolve the drama.