Found out about the affair through a shared cloud account, but now I'm stuck in the 'what do I do next' phase.

I (32M) have been married to my wife (31F) for five years. We’ve always had a solid foundation, or so I thought. Everything seemed fine until last Tuesday when I was trying to clear out some old photos on our shared iCloud account to make room for some work files. I stumbled onto a folder that wasn't labeled, just a string of random numbers and letters. When I opened it, it wasn't photos of our trips or our dog. It was hundreds of photos and videos of her with someone else. Not just casual stuff, but clearly a long-term, physical affair.

I haven't confronted her yet. I know that sounds crazy, but my brain just short-circuited. I spent the last few days playing detective, and the deeper I go, the worse it gets. I found messages that go back at least eighteen months. This wasn't a one-time mistake or a drunken lapse in judgment; this was a whole separate life she was building while sitting right next to me on the couch every night. The level of calculation involved in the lies is what's really eating me alive. She'd tell me she was working late or out with friends, and while she was actually with him.

I'm currently sitting in my car in a grocery store parking lot because I couldn't stand to be in the house with her for one more minute. I feel like I'm losing my mind. Part of me wants to go inside, throw everything I own into trash bags, and walk out without saying a word. Another part of me wants to sit her down and demand every single detail, even though I know that will probably just traumatize me more.

I don't know if I should go straight to a lawyer, or if I should try to talk to her first to see if she even admits to it. I'm terrified that if I confront her now, she'll just gaslight me or try to flip the script and make me feel like I'm the one doing something wrong by snooping. I've already backed up all the evidence to a separate drive so she can't just delete it if she realizes I know.

Has anyone else dealt with this kind of long-term deception? How did you handle the initial confrontation? I feel like I'm standing on the edge of a cliff and I don't know which way to jump. Do I try to save the marriage if she's even capable of being honest again, or is it better to just cut ties immediately before things get even more complicated? I'm completely lost and honestly, I'm just numb right now.