Sorry for my delay in offering you support. There are so many issues to comment on in this current event I am not sure where to start!
So here goes:
This smells like BS on his part. I have never heard of any man wearing an engagement ring. This is a way to create some drama on his part.
Who gets engaged while their child is in intensive treatment? I know most moral, decent people would be concentrating on the well being of their child, not on their romantic life! This engagement could not wait until DD was in a better place?
This is a way to put the focus on how important he is in the whole family drama. Okay I know this sounds weird but as long as he pulls stunts like this the focus (good or bad) will shift to him and his behavior.
It is another opportunity for him to prove how selfish you are to try to interfere with his happiness.
You have no idea what he has told his new victim...oops meant fiance.
You ex, like mine is the king of spinning an amazingly credible story in the short term.
Take care of your children. This will unravel for the NPD jerk.
Take care NIK!