Mood swings are the norm for a person in crisis. One minute they are up and the next they are all over the place. It's not about you, but how they are feeling. If you could get inside their heads, you would see that nothing is in its proper place, i.e., everything is a mess. They are hormonal, they are emotionally fragile and everything sucks in their world.
It doesn't matter what the situation is, if he's having the mood swings, he'll come out swinging and won't care what he says or does. They have no control over them because it's all about his emotional mind set at that time. They are like two year olds you haven't learned out to deal w/life in a normal manner.
The best thing you can do is either avoid him, switch the conversation up so that he has to stop and think about what you just said or listen to his venting and provide no comment. The more you try to defend youself when he's like this, the worse he'll be.
I'm sorry you've had to be a witness to this behavior, but it will eventually die down as he moves through the crisis. Please do not take what he says personally. He's a time bomb right now, ticking away, and trust me, he will explode around others as time goes on because he will not be able to control the anger. This type of behavior sets him up for the next stages that he will be experiencing while angry.
Step back and allow him to shadow box w/himself in the ring. You do not want to be his sparring partner when he's like this.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
