Test to see if Excel sheet is open before loading worksheets to listbox

Question

I have a function that opens an excel file and loads the worksheets to a listbox.

I am noticing that if the workbook is open, when I go to load the worksheets, I get an "out of memory" error

Is there a way to test I the excel is open, after the user selects it from the dialog, but before I try to load the worksheets, so I don't get that error?

Private Sub cmdFileDialog_Click()
  
   Dim fDialog As Office.FileDialog
   Dim varFile As Variant
  
   ' Set up the File Dialog.
   Set fDialog = Application.FileDialog(msoFileDialogFilePicker)
 
   With fDialog
 
      ' Allow user to make multiple selections in dialog box
      .AllowMultiSelect = False
            
      ' Set the title of the dialog box.
      .Title = "Please select an Excel Timesheet File"
 
      ' Clear out the current filters, and add our own.
      .Filters.Clear
      '.Filters.Add "Access Databases", "*.MDB"
      '.Filters.Add "Access Projects", "*.ADP"
      .Filters.Add "Excel Files", "*.xls;*.xlsx;*.xlsm"
      .Filters.Add "All Files", "*.*"
 
    If .Show = True Then
        Me.txtFile.Value = .SelectedItems(1)
        LoadWorksheets
       Else
         MsgBox "File Selection Cancelled."
      End If
   End With
End Sub

Private Sub LoadWorksheets()
    Dim xl As Excel.Application
    Dim xlWrkBk As Excel.workbook
    Dim xlsht As Excel.worksheet
    Dim strFilePath As String

    strFilePath = Me.txtFile.Value
   
    Set xl = CreateObject("Excel.Application")
    Set xlWrkBk = GetObject(strFilePath)
       
    For Each xlsht In xlWrkBk.Worksheets  'Errors on this line
        Me.lst_worksheets.AddItem xlsht.Name
    Next
End Sub