How to call Button_Click from Ribon-Class in c# Office Add-in?

Question

I'm working on an Office-Add in for Microsoft Visio. I am starting my Application by Clicking on a Button of the Ribbon-Control in MS Office. My problem is, that at a certain Point I want to call a StopButton_Click Method located in the Ribbon-Class (just like the Start-Button, clicked earlier) from another class Class2. However this is not possible without creating another instance of the Ribbon-Class in Class2 to which I refer by calling the StopButton_Click. Right now, my code looks like this:

public partial class Ribbon {
     public void StopButton_Click(object sender, RibbonControlEventArgs e) 
     {
          //Button to Stop Application
          //enable/disable Ribbon Control Buttons
     }
}


static class Class2 {
     //some Code
     Ribbon r = new Ribbon();
     r.StopButton_Click;
     // some more code
}

In the StopButton_Click Method I am enabling/disabling certain Buttons of the Ribbon-Control of MS Office (depending on whether the app is started or stopped).The Problem now is, that the Application Stops, but the Buttons in the Ribbon-Control are not changing. I think it's because I am calling the StopButton_Click on another Instance than the one I started the Application.

Is there a solution for this? Like calling the StopButton_Click in Class2 without creating another Instance?

Thanks in Advance!