This is gonna be a tad long, so please bare with me. My best friend and I used to have a small but close friend group in our home town. Then we went to two different universities quite far away and I became a bit less close with people back home. My best friend though, still put in a lot of effort with our friends back home and they never put as much effort in, until one day I decided I thought that was kinda bullsh*t and really started to phase out the friendship. It's been a few years now, but my best friend still talks to them regularly, and while I don't hate them, and don't hold anything against them, I can't help but feel this resentment and jealousy towards one of them in particular, even though she's definitely become a better person. How to I let go of that? She might be moving closer to where my best friend and I live and I'd like to actually be friends with her again, but those feelings won't go away. Halp, thank you

TL:DR I used to be friends with someone but lots has happened and even though I don't hate her and she's clearly become a better person I still feel resentment and jealousy when my best friend talks about her. How do I let go of that? Thanks