Need advice on my ex?

Me and my ex were together back in high school we've been talking off and on since we broke up 5 years ago. One of the biggest reasons we broke up was she was very immature and constantly flirted with other guys and at one point cheated on me when we had to be long distance for 3 months. I never felt I could trust her after that. But we started talking again earlier this year and hanging out and she says that she's changed and that she's only ever loved me and I believe her. We were kids back then and I know she regrets a lot of what she use to do. And I want to trust her but part of me still feels insecure and that something might happen. Do you think people can change in 5 years? And should I believe her when she says she changed?
Need advice on my ex?
Add Opinion