Thankyou, for the very helpful replies, and more to think about

Yes, the chameleon, that is exactly what seems to be occurring.
The picture of the puzzle pieces works very well for my situation in that I was happy when we met - except for one missing piece. I was wishing for companionship, as I wanted to share my otherwise good (to me!) life. It would appear that my ex's wish for companionship was about a lot of other things... .such as needs fulfillment, dramatic re-enactments and projections for BPD reasons, that kind of thing. I cannot know for sure, but he appeared to be with me for reasons very unlike my own motivations for relationship.
When questioned, in words we are of course the same in motivations (the chameleon matches), but his BPD directed actions spoke very aggressively to the contrary.
But maybe the words are truth, and BPD is a deceptive overlay on his real selfhood.
He did objectify himself, and does so less now. I did not feed this objectification and he found it immensely disturbing. As for my ego, I think it was reduced by having all of my life practices, capacity to work, rest, function,... when and how I chose, stripped away from me. Everything I had chosen to keep in my life, and with which I subsequently identified myself, was forcibly removed. My choice became: do I take care of this person in extreme need, or do I maintain my own life?
So, like a parent of a child with special needs, I lost my identity that way. That's ok, I am learning so much about my own vulnerabilities/weaknesses now that I am glad to be starting again from scratch. I didn't even know my ego had anything to lean on at all, until this relationship. Or that I had/have codependant tendancies.
There is so much to process.