Lies About the Past Despite Multiple Chances to come clean

I (M36) and my partner (F36) have been together for 13 years, married for 8, and we have a 3-year-old son. We were close friends during high school as well. We talk a lot, share everything, and had an amazing life the way we dreamed about. Then, a story from her past came along, destroying us, everything we were and we had. It was about an affair she had during her college. Both of us had multiple affairs in the past we chat a lot about it for fun. After we started living together, while we were casually discussing our past relationships, her story about this specific affair was not really convincing. She said it was just a small affair and ended fast. But later, I came to know from multiple sources coincidentally that it was something more than that. I confronted her with this information, and she admitted to the affair and being physical (but denied having sex), she cried a lot, apologised and I decided accept her past forgive her mistake. After a few months, just before our engagement, I asked her about that again, and confirmed that they did not have sex. I told her if I ever found out that this was not true, things would end there. She said she understood the seriousness, and eventually, we got married.

Now, after 8 years, during a long drive, this discussion popped up from somewhere, and I sarcastically said her answer about sex was not convincing and pressed a little hard on that. But she stuck to her same response, even after I asked multiple times. Later, I told her this was the last chance in her life to come clean, and she didn’t change her story. I was happy relaxed, then after a minute of silence, she shouted, “We had sex!” I didn’t know how to respond to that. After so many lies, promises, and gaslighting, she finally accepted the truth. Something deep in my mind said there was more to the story, and I kept pushing her to tell everything. Then I heard about a 1.5-year-long affair which involved physical also. My life has not been the same since then. I don’t know what bothers me more, the fact that she lied, and our life started based on lies, or just the fact that she had sex with someone before me. I’m feeling like the last 10 years of my life have been rewritten. I remember her face every time she lied to me. Precisely 8 times in these years. My memories of our first sex are not the same. A lot of our past memories seem fake to me.

This is the only thing she lied to me about in her entire life, and I really know that she loves me more than anything in the world and she is ready to give her life to correct the mistake (lying to me) she made. But it’s still difficult for me; I see her as a different person now. Someone with a completely different past, maybe not the same person I fell in love with. I’m going through soul-crushing pain, getting panic attacks, and drowning in depression. I wish i could explain my pain in words here, but it’s beyond words and I’m sure people here can understand it more than a therapist who has not gone through something like this. I really want to get my life back, but I don’t think it is going in the right direction. I know a lot of people might say it’s her past and ignore it, I would have,if it was honestly communicated to me. As I said earlier, when she accepted part of it for the first time ( about getting physical but denying sex ) I trusted her and chose to forgive her.

Everything triggers me now: watching other couples, romance movies, songs we used to listen to together, even memes about virginity, can’t even watch porn. Already doing therapy, but not really helping. I'm a complete mess. Help me.