Leaving would/will be hard but it sounds the only way. And it will be hard to explain to your youngest. (I don't recommend running right into another relationship, that will be hard on the youngest too...) but you can---look for information on talking to kids about this and ensure he will have contact with dad, when he is not acting out---this makes everyone sad, and the six year old should not have to worry about whether dad will be ok or not---or begin to assume some responsibility for that---....my heart goes out to you. You could start with a separation. Give everyone time to adjust to being apart