How to return an instances position in a table?

Help and Feedback Scripting Support
#1

I don’t know if I said the title right lol, basically I am working on this GUI where you can select multiple things, and unselect them, and if you select it adds the object to a table, and if you unselect it needs to remove it from the table. Here is my script:

selectedCrystals = {}

for _, v in next, script.Parent.MainFrame.Buttons:GetChildren() do
	if v:IsA("TextButton") then
		v.MouseButton1Click:connect(function()
			if script.Parent.MainFrame.SelectShow[v.Name].Visible == true then
				script.Parent.MainFrame.SelectShow[v.Name].Visible = false
				table.remove(selectedCrystals, Dont Know how to get the Position)
			else
				script.Parent.MainFrame.SelectShow[v.Name].Visible = true
				table.insert(selectedCrystals, #selectedCrystals + 1, v.Name)
			end
		end)
	end
end
#2

table.find(list, argument) I feel extremely dumb right now lol