What to do about my father?

Tell him how it is in plain english. Hes a grown man, he can take it. I had to speak plainly with my mother after her last divorce as well, she was driving all her kids nuts. It helped a lot, shes well on her way to getting her life back together, but Im willing to bet she would be wallowing in her misery still if someone hadn't been honest with her about how she was making everyone else feel.