My first relaspe as a Buddhist

Well, today, my sister was trying to get home by bus, but an insensitive bus driver wouldn't let her because:

1. Her transfer expired, so she had to wait.

2. The black line of her bus ticket was scratched, so she couldn't get on.

So, I was pissed. Yes, I having difficulties with her, but she's still my blood and I don't want bad things to happen to her. The next thing I did was call MAT and used very colorful language to express my frustration. Nam-Myoho-Renge-Kyo didn't come into my mind, just that my sister was did wrong and the people who did it(MAT) deserved to be cussed out. Have you guys ever had a relapse and if so, how did you deal with it?