Mopsey, I wouldn't worry too much about his mood swings. I was reading an article in the Post over the weekend about mood swings and adolescents. Guess what the contributing factor was? Stress. Let him cry to his heart's content. He made this mess and now he must clean it up.
Listen to what your SIL has told you about his past behaviors. Sound familiar? He's in desperate need of a 2X4 up beside his noggin. He's trying to grow up and doesn't know how to go about it.
As for your daughter, she should have known better than to ask about skipping school this week, especially with all of the testing being done all over the country. Stick to your boundaries or your daughter will be acting out just like her father, especially if they hang together for very long.
I feel for you. It's a tough journey and until this man hits bottom hard, he's going to be acting out all over the place. He's going to have to realize at some point that the world doesn't revolve around him.
