First suggestion, if you're able to, is to upgrade to .NET 3.5 or higher. Working with XML will be much less frustrating.
Are you wanting to parse the selected item and break the inner text "12,13,14" into three parts? If so the following should do what you want (provided you upgrade to the latest .NET version).
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
Dim Element = XElement.Parse(Me.ComboBox1.SelectedItem.ToString)
Dim ElementValue = Element.FirstNode.ToString
Dim Values = ElementValue.Split(","c)
For Each Value In Values
Debug.WriteLine(Value)
Next
Dim Value1 = Integer.Parse(Values(0))
Dim Value2 = Integer.Parse(Values(1))
Dim Value3 = Integer.Parse(Values(2))
Debug.WriteLine("Value1={0}; Value2={1}; Value3={2}", Value1, Value2, Value3)
End Sub
Hope this is what you're asking for. If you are unable to upgrade to the latest .NET version, let me know and I will re-post code for .NET 3.0.
Cheers!