Tearing up one's step father's visa

My mom married someone who my mom brought to uk. When time came for his visa to be renewed my mom had two choice one to give him permanent or just extend. My mom wanted to give him just extended because she did not like his behaviour as it changed as he was already married as well. According to my mother he threatened her and said if you don't give me permanent visa I will tell everyone you married me as it was kept a secret. Also he said when you go back you watch what happens something along the lines. Due to the threats and pressure she applied for permanent visa but was very unsatisfied so she asked me to help her to collect his letter and destroy it. Which I did and due to destroying the letter he was deported as he had overstayed. Am I sinful as I just helped my mother. Now my mother does not speak to him for obvious reasons, there is no contact so if I had said something in anger to him am I sinful?