Am I obligated to my aunt's husband and my aunt, and will I be punished if her husband saw the offensive clips and did not speak?

You are obligated to repent to Allah for opening the bad clips. You did well when you ascertained that the divorce was not due to these clips. It remains that you used the woman's phone in a way that is not permissible, so seek her forgiveness for that if she had given you permission to benefit from her device. Otherwise, seek her forgiveness for benefiting from the device without permission.