I'm unsure about whether I [19M] should break up with my girlfriend [18F].

**TL;DR:** I checked my girlfriend's phone, found messages about her ex that left me uncertain about our relationship. I (19M) have been in a long-distance relationship with my girlfriend (18) for about seven months. Recently, I visited her in her country, and things seemed to be going well. One night, after she fell asleep, I made the poor decision to look through her phone. She has reassured me that she wants to stay together, so now it's up to me to decide how to move forward. What I discovered was troubling: she had conversations with friends about her ex, speaking highly of him and mentioning things he has that I don’t, like financial security. Although she claimed she would never cheat and has no intention of rekindling their relationship, I can't shake the feeling that she's still emotionally attached to him. When I confronted her, she was very apologetic, suggesting it was a momentary lapse in judgment. I told her I needed time to process everything. After I got home, we discussed it over text, and she acknowledged my breach of privacy while revealing that she, too, had been contemplating a potential breakup. Now, several weeks later, I can't stop thinking about the messages I saw and some other things she's been dishonest about, like her past relationships. I'm torn between wondering if I should end things, if I was wrong for looking through her phone, or if this relationship simply isn't working. I would appreciate any advice on how to navigate this situation.