I Discovered My Wife’s Secret—and Now Our Marriage Is Falling Apart

So I (M28) have been married for 1.5 years now. It was an arranged marriage, and from the beginning, there have been problems between my family and my in-laws. Despite all that, our marriage took place, mostly because I managed to take care of things and bring both families to a common ground.
My wife (23F) had a relationship with a family relative, which she hid from her parents. I have no clue why she agreed to marry me—someone who is not very good-looking—but I am guessing it was due to family pressure.
Fast forward to 8 months into our marriage, I never checked her phone or answered calls regardless of where they were from. However, curiosity got the better of me when I saw a notification pop up saying, “I still miss you so much,” which someone had reacted to with a sad emoji. I unlocked her phone and discovered that my wife was still in contact with her ex. They were discussing me, sharing some ugly and compromising photos of me, exchanging intimate photos of themselves, and having inappropriate conversations.
This completely broke me. When I confronted her, she begged for forgiveness and promised never to talk to her ex again. I forgave her, not because I could forget what happened, but because of the shame it might bring to both our families.
Since then, we argue every now and then like any other couple, but I have never taunted her about her past. To me, the past is the past; it is the commitment to the future that matters. However, my parents have been another challenge. My father has a habit of making jokes that are sometimes inappropriate or hurtful. I have always told her to ignore them to keep the peace, but she often doesn’t.
Today, my father made another such joke. It wasn’t a nice one, but rather than talking to me first, my wife called her parents and had them come over to our house at 11 PM. I was shocked and terrified. This led to a big argument between me, my family, and her parents. During the discussion, I was forced to reveal her past relationship. This was embarrassing for her parents, but they took it well. They spoke to their daughter and explained that she should behave better with my family and avoid repeating such actions.
After the argument, my parents spoke to my wife and suggested that we let bygones be bygones and start afresh. I thought things were settled. But to my surprise, when my wife and I returned to our room, she started arguing with me, accusing me of ruining her life and damaging her relationship with her parents by revealing her secret affair. She even said she would seek revenge.
I am at a loss about what to do. After everything, she is still adamant that it is all my fault. Please help me figure out what I can do.