Getting a new protagonist when I wish I could “continue” the story with a retired one.

I only just started working on this new story of mine, and I noticed that the main character is basically the main character from the previous story. I’ve been writing that story for a few years now, and it’s up in the air about what will happen to it. I just really want to continue in the world, and I want to use some of the main character from the previous story AND perhaps they would even be the main character. That’s not what I did with the new story though. Instead, the new protagonist is someone that would be a side character in the other story, and I want to explore them. I also want to write this story first before I go back into the other one. I’ve gone back into the other story a few times already, but I always end up getting distracted and working on other things. That story is important to me, so I want to work on other stories before I go back to it. It feels like I’m being selfish and I want to just research how to take down an entire firm to get back to what I really want to work on. I feel guilty for not going into “the good story” first, but I know I’m not ready for it yet. I’m not a professional writer just a fan fiction writer, but I am wondering how authors deal with this when they start a new story.