MY MOM has an AFFAIR+MY DAD LOST JOB=MY LIFE RUINED

Hi, my name is Rebecca, and the story I want to share is a bit sad, but I need your advice.
I had a great home life; my parents were my best friends. I know that sound corny, but it’s true. We did everything together, and they were always there for me.
While we were all very close, I had a really special relationship with my Dad. He’s one of those guys that you can just talk too. He was very open and honest and was a fantastic listener. He would help anyone, and even when he came home tired from work, he still always had time for my mom and me.
Dad always went above and beyond for my mother and me. He threw us big parties on our birthdays, he always had the most thoughtful gifts, and while a lot of Dads like to go out with their friends or sit on the sofa watching sports, my dad liked to play board games with my mom and me. He was the best.
My dad was a researcher and had been working for the same company for over twenty years. One day, my dad came home early and told us that the company was being sold and had laid everyone off. He tried to put on a brave face, but I could tell that he was upset and a bit scared. My family was strong, though, and I thought we would get through it.
Dad has had a really hard time trying to find work. Because of his experience, he can’t bring himself to take a low paying job, and he doesn’t want to leave his field to try again somewhere else. He suggested we might move but my Mom doesn’t want to as we live close to her family. I don’t want to either as all my friends are here, but I would if it meant my dad would be happy again.
Lately, he seems to have given up. He’s really cranky and doesn’t want to play games with us anymore. They don’t think I can hear them, but at night my parents fight about money. Things are getting really tight, and my Mom is getting worried.
My Dad left one morning to try once again to find a job; my mom got on the phone. She called someone and talked about our situation. She started to cry, and I thought I better not hang around to watch. Later, she seemed to be in a much better mood.
I asked her who was on the phone and she said that a friend of hers from college had a big company and so she called him to see if he had any jobs. He did! He offered my mom a job that pays really well, and she could start the day after tomorrow. She said that the guy was going to come over to sign the paperwork tomorrow. I was excited for her.
That night at dinner, Mom told dad about the job, he was happy for her, but I think he was still so upset about his own situation that he felt hurt by it like he couldn’t provide for us.
The next morning, Dad left and said that he was going to a Business Expo to try and see if he could drum up some work and wouldn’t be back till late. I went to school and Mom was cleaning the house to try and impress her boss.
All the drama at home has been very stressful, and it must have worn me out because I felt very sick at school. I went to the nurse’s office, and they tried to call my mom, but she wasn’t answering. They got a hold of my dad and he told them to send me home.
Luckily, I don’t live that far from school. I got home and I notice that there was another car in the driveway. My mom’s new boss must have come over. I went inside and they were nowhere to be found. I was feeling sick and didn’t think too much about it. Then, I heard a noise coming from the kitchen. I thought that maybe they were having coffee in the kitchen. I didn’t want to disturb them but when I heard a plate smash, I knew I had to check it out. I looked through a crack in the door and that when I saw what was really going on. My mom was having sex with a strange man on the kitchen table! That’s where I eat breakfast!
If I was feeling sick before, I needed to throw up now. I raced out of the house and threw up in the rose bushes outside the door. I don’t think they heard me because I could see hear them doing it from outside. Is this what my mom was doing to get the job? I couldn’t go back inside so I walked to the library and did whatever I could not to think about it.
What am I going to do? Mom didn’t know I had come home early, but Dad did and was going to talk about it when he got home. I tell my Dad everything, do I tell him this? How is this going to affect his already terrible mood? Is this Mom going above and beyond to keep our family going? I don’t know what to think anymore. What do you think?