What can I do when my dad is dying and his wife won't let his 8 kids see him or visit?

We have not been able to see my dad for years cuz of her and he she moved out of state now she's back. His wife is disabled mentally. My dad can not eat even move on his own she won't allow anyone to see him. Today we received a text from her telling us she's haveing a feeding tube put in or he will die. Now she told me my dad did not want and tubes at all. Plz anyone have advice.