I'm sorry for everything you are going through.

My take is that he is unable to have talk with you about you. Probably because he is depressed and is not really coping with his own needs, he can't look after yours. He feels guilty about this, but can't change it. Hence his talk about the need to let go- he can't give you what you need.

On the other hand, he doesn't like the consequences of this, that he would lose you. Hence the swings between being super-nice to you (maybe you won't have needs if he is super-nice to you), and hanging out with another woman (it will take a lot longer for that other woman to find out that he can't look after her needs).