How do I deal with this?

If I were you, I would sit down and have a serious talk with him but be sure to use only a kind and loving tone. It's very hard when men retire. They're used to working, being needed, having so many in the air at one time. Now, he has nothing to do and is taking out his feelings of helplessness out on everyone around him. He needs to find hobbies! It's always a hard transition when someone retires but he needs to understand how it's effecting everyone. He may not even be aware of how much he's changed.