Part of her effort to reassure me includes the freedom to go through her phone when I feel something is off, to confirm for myself and to reassure myself.
This is a the perfect setup where you get complacent because of the false sense of security she instilled on you. There's a phone feature where you can setup your phone to create a "virtual space" that works as an entirely different phone that has a different memory to store her contacts, conversations, apps, videos and more. By giving you the illusion of having "control" over her phone, she can literally manipulate you to her whims.
Confirmed timeline as after she started dating a previous partner, and felt sick to my stomach at what I read.
Do I need to say more?
When I repeated that I need her help she started raising her voice, then accusing me of spinning this shit and bringing shit up at the worst time and for snooping and going through her phone - to which I argued she insisted I do, and apparently she meant that I do that for only one person
Okay, I'll say more. She doesn't like being confronted and instead gaslighted you because she already knew shit hit the fan, and maybe she can throw shit to your direction. It means she's willing to go that direction so she can continue with her stuff without risking losing you IF you fall for her antics.
I said if she continued to shout at me, repeating she doesnt remember and accusing me of just snooping and bringing shit up, then I would leave.
This makes much more sense. You don't have a reason to stay in a relationship where you can't fully trust your partner because of her previous mistakes where she did something that would MAKE you think about leaving her.
I am now dressed, and wanting to leave the house, but am hesitant because of some chance I might be misunderstanding the whole thing. I don't know how, because my gut is usually right about these things, but I can't just leave right now.
You give yourself enough time and space TO HEAL. That's how bad your relationship went, and you can't blame yourself on how your relationship turned out. Why? Because in times of doubt, you should be TRUSTING your partner, not DOUBTING her. She gave you reasons to doubt her. Is that being trustworthy? If you come back to her, would you still have the peace of mind to last a lifetime with her?
Bottom line: you know better. You asked for advice, and this is my two cent's worth.