What would you do if you found out your husband saved pictures of another girl to his phone

We’ve been married for 3 months and together for 5 years

I’m 25F and he’s 27M

Was going through my husbands phone (we have an open phone policy) and in his google photos (which backs up his iPhone photos and he forgot to delete) and I found several screenshotted pictures of the girl he was talking to before we started dating.

It told me he screenshotted them July 16th. I was like “so who’s this?” at first he said he didn’t know and that turned into “probably someone I talked to” and then that turned into”it was so and so” he lied about why he had the pictures. He came up with some whole excuse about how his phone randomly backed up the pictures. Then he finally came out and said our relationship was a mess at the time so he was looking at her and reminiscing about the past and how things were easy and stress free back then. I asked for her last name so I could contact her and he ‘forgot’ and couldn’t find her on FB anymore. He said he found her because he was going through his friends list, didn’t realize they were friends still and started looking.

But why screenshot the pictures? That’s so weird to me. He even cropped her out a picture with her family? Like why take the time to do that if you didn’t wanna keep looking or weren’t doing something weird.

He also privated his friend list on Facebook a long time ago, claiming that he didn’t want people snooping his profile.

A few days before he took the screenshots he posted that we got married and changed his status so I’m like wtf?

This was weeks after I miscarried and we got married. That was hurtful as fuck.

My dad talked to him and said “in my honest opinion, I think he did something weird and stupid but if I was in your shoes I would forgive him and move past it. Me and your mom went through something similar where we talked to people from our past” and now they have a great marriage, but I’m 25 and don’t want to end up staying with a cheater.

I spoke in confidence with a close friend and she thinks I should leave him… it feels like a double edged sword, if I divorce him and he’s innocent and made a mistake then I lose a great guy. But if I forgive him and stay, he could be a cheater.

He swears he didn’t cheat because he knows I would leave him and that we’re always together so how would he cheat.

And then he’s like “I love you and want to work on this and move on but if you leave me, I wouldn’t blame you”

He lied at first before confessing to me that he was looking at her because he was reminiscing about the past when things weren’t stressful and he could do whatever he wanted. He said he realized quickly it was wrong and stupid and deleted the pictures. I asked for her name over and over so I could contact her and ask her if they talked but he insisted he forgot and couldn’t find her.

I don’t want to stay with a cheater but I also don’t want to lose him if it was just an honest mistake.

I ended up finding her instagram and her name was totally different from what he said it was and the girl graduated high school LAST YEAR. when I told him this he said he had no idea.

He said him and the girl only talked for a week on the phone and never FaceTimed so he didn’t know.. he says he was catfished

But my question is why would she still be posting on Facebook under this other name to keep up a ruse from almost 6 years