I have been in your shoes and know the feelings you have. It is so hard to "want them to go" yet we know that our loved one's suffering will only depart by taking hold of God's hand and completing life as He intended.
Praying with you for a swift passage for your Dad to His caring hands!
Your Dad is not leaving you, but simply beating down the path for you, as he has all your life, so that you may follow when the good Lord decides it is time for you to reunite.
I think of, and often talk to, my own parents whom have gone on ahead years ago, on a weekly basis, and no one will ever convince me that they do not hear.
We WILL rejoice, all together again, as He has promised.
God Bless
Steve