Decay/cavity in front top tooth just below gumline, how fixable dose that sound? (Need reassurance)

I understand it probably depends, but I'm very anxious and could use some reassurance.

So I (M20) wasn't taking a lot of care of my teeth In the past year and recently have changed my habits and I've gotten better with brushing my teeth everyday, but unfortunately, it's too late for one of my teeth (as far as I know).

I'm not sure if there's a certain name for the tooth. But my tooth that is at the very front. The top has a hole in it; Not all the way through but it's probably the biggest cavity that I've ever had and I know that it needs a fidling.

I'm lucky that I have enough money to get an appointment for for my dentist to get an X-ray of my teeth, cleaning and tell me what we need to do. Where this tooth Has the cavity/decay so close to the gumline I've never saw something like that happened to somebody before and I'm just kind of worried that they might have to extract the tooth or something if it grows too much before they can fill it. (It's not like half the tooth, but pretty good size)

I can't really get a good picture but by my description; How fixable does that sound? Do anybody have any reassurance for me?