How to close infinite loop on button event - powershell

Question

One of my admins wanted a little script, that visualizes if a certain process is running. I managed to accomplish this by creating a systray icon which visually changes according to the status. Now my problem is that I don't have a lot of experience working with GUIs and I don't seem to be able to exit the program when a certain button is clicked.
Sourcecode is here:
#Declare Assemblies
[System.Reflection.Assembly]::LoadWithPartialName('System.Window.Forms') | Out-Null
[System.Reflection.Assembly]::LoadWithPartialName('presentationframework') | Out-Null
[System.Reflection.Assembly]::LoadWithPartialName('System.Drawing') | Out-Null
[System.Reflection.Assembly]::LoadWithPartialName('WindowsFormsIntegration') | Out-Null
#Add an icon to the systray
$bitmap_green = [System.Drawing.Bitmap]::FromFile('C:\Temp\green.png')
$hicon_green= $bitmap_green.GetHicon()
$icon_green = [system.drawing.icon]::FromHandle($hicon_green)
$bitmap_red = [System.Drawing.Bitmap]::FromFile('C:\Temp\red.png')
$hicon_red= $bitmap_red.GetHicon()
$icon_red = [system.drawing.icon]::FromHandle($hicon_red)
#Create Systray object
$Systray_Tool_Icon = New-Object System.Windows.Forms.NotifyIcon
#Mouseover text
$Systray_Tool_Icon.Text = "MOBS läuft"
$Systray_Tool_Icon.Icon = $icon_green
$Systray_Tool_Icon.Visible = $true
$Menu_Exit = New-Object System.Windows.Forms.MenuItem
$Menu_Exit.Text = "Exit"
$exit = $true
$contextmenu = New-Object System.Windows.Forms.ContextMenu
$Systray_Tool_Icon.ContextMenu = $contextmenu
$Systray_Tool_Icon.ContextMenu.MenuItems.AddRange($Menu_Exit)
$Menu_Exit.add_click({
$Systray_Tool_Icon.Visible = $false
$exit = $false
})
do {
$running = Get-Process mobsync.exe -ErrorAction SilentlyContinue
if (!$running)
{
$Systray_Tool_Icon.Icon = $icon_red
$Systray_Tool_Icon.Text = "MOBS läuft nicht"
}
else {
$Systray_Tool_Icon.Icon = $icon_green
$Systray_Tool_Icon.Text = "MOBS läuft "
}
[System.Windows.Forms.Application]::DoEvents()
} while ( $exit -eq $true)
My idea was to create a do while loop which continuesly runs until the admin presses a button in the contextmenu of the icon. So in essence I built an infinite loop.
My problem is, that the add_click isn't working as I expected. Can somebody give me some advice or some hints on how to properly close my loop on the click event?
Thanks in advance.