I agree. I think sending a caring, thoughtful card with a personal, handwritten note from yourself expressing your care and concern over his situation is a great way to handle this. I am sure he will appreciate the gesture. I think you are right to protect your well-being and your mental health in other ways, and that it's understandable why you want to hold him at arm's length. He may want you to reach out to your father, but really it's not his business. I completely understand why you don't wish to reconnect with your dad.

When it comes to abuse and harmful actions by others, we must protect ourselves.

(((((Hugs))))))