Can I stop Dad's irresponsible spending?

My father is 69 years-old, has lots of credit card debt and has some real estate that was purchased with my mother. My dad is my mother's "survivor" so he cashes her retirement check every month. My mother would have preferred that (small) retirement money to come to my sister and I but was hopeful my dad would share that with us if she ever died before he did. Recently, my dad has become very close to a certain woman who has made herself very present in his life. Before her, my dad never would take anybody to his two country clubs, now he is bringing her there and has even taken on more debt in order to pay for dinner invitations for this woman. He is behind his basic services (water, telephone, etc.) and alleges he does not have the one-off jobs he used to have. That is why he is so behind in payments (yet he has been going out for dinner). My sister and I are worried about his finances as this is a never-ending cycle with his increasing credit card debt. I tried paying a lot of things off myself to make sure that he could be up-to-date with his basic services but he just keeps falling behind. He will not admit to us that the money is going somewhere "else". Is there anything we can do to stop him from getting credit cards? In the past he pawned our mother's jewelry without telling us and I had to "rescue it" from the pawn shop. We are worried about his finances going forward. Is there anything we can do? Talking to him does not help much, he thinks he knows it all and his acquaintance with this woman does not help out at all.