Ahsan Allah Ilayk Ustadh Al-Karim, a brother asks: While looking at family photos in our dads email with permission, by accident we saw clear texts of him trying to have a haram relationship many yrs ago despite being married to our mom. How can my mom, siblings, and I deal with the tension at home?

What I understand from this that this was in the past and not anymore. Therefore, you should totally ignore this as if you have not seen it, and don't let the shaitan seperate you for a mistake in the past that he stopped now, forgot about therefore gave u permission to look in his email, and maybe he even repented from this. Never shame someone and cause problems for someone who have repented from such a sin. May Allah rectify our and your affairs, ameen.