B is simply projecting all of HIS negative thoughts, feelings and actions he is feeling onto you. These are really all clues to what is going on in his head. When he says, YOU are not worth the effort, he is saying, he feels HE is not worth the effort. I would put more emphasis on the things he says while crying, than while angry. BUT, filter all of it until he proves himself with actions.
When he lashes out don't instantly defend yourself. Validate! Let him know you are listening and if things get out of hand let him know it is unacceptable and set boundaries. As humans and emotional creatures we get angry. Don't let yourself be pulled into the emotional trap. By confronting him in a lie, it caused him to project his own negative actions on to you. ** He said all I have beendoing is telling him that he is not trustworthy and nagging him and I was a bitch and needed to grow up. ** I read, Lisa, I'm an ass, I feel like no one trusts me, I wish I could grow up and do things right." Also, recognize he WILL sway back and forth from good and righteous, to down and dirty. Your role is to provide him consistency. Consistently be the one he can trun to, the one he can follow, the role model he never had to develop the relationship skills his family life did not provide.
His role is to recognize the consistency and gravitate toward it. In time, the hope is he will grasp it and recognize it's virtue. He will lie, he will disappoint and don't trust him with your heart while he is fighting his own battles. Instead, show him you believe in him by assisting him any way you can. Make the effort, he will see it, hopefully he will respond to it.
You and he are trying to reverse years of issues, many of which started long ago. This will be hard for both of you, but it will be far more difficult for him to turn things around. You have shown him how committed you are to family, he knows you are the rock of the relationship. I'm cetain he has signs of depression and along with that he feels inadequate. When he begins to beleive in himself, just as we as DBer's have been taught to do, he will recognize his accomplishments. Baby steps. He needs to build on each and every small success he has, Help him recognize them and praise them when they oocur. Nuture the good, validate, but ignore the bad.