Insecurity is what my daughter (my post in BP, which you answered) is going through and a big part of what I went through 20 years ago. Since no one answered, and inspite of my answer not being "in keeping" with the type of answers on this board, I'll put in my two cents.
When my ex-husband left his first wife--she ended up in a psycho ward and became a full blown alcoholic.
When he left me, I was nuts too, but hid out, to keep from ending up in a psycho ward.
When he died after an extended illness, he left his third wife sucked dry and "out there" somewhere.
Today we have all pieced ourselves back together and are living decent lives. The first is no longer alcoholic. I'm happier than I've ever been, and the third is still out there somewhere, but funtioning again.
Even though we were competent, we must have begun our relationships with him in insecure states. He used us "all up" and used our competences to further himself. WE LET HIM. WE OFFERED OURSELVES UP TO HIM, THE GOD OF OUR LIVES, JUST TO BE AROUND HIM. And he used us over and over.
In the end, I was so confused, scared, and weakened I couldn't judge anything, make decisions, or help myself. Eventually I ask a girlfriend, which businesses were run by the most mentally healthy people in town. Then I frequented those, so I could see what being around decent people was like, and so that I could be treated decently. There were lots of other steps after that, but that was still one of the best.
I remember one time saying something to the manager of one of the business and the look on his face told me that I'd just stepped over some imaginary boundary. You would have thought I was dracula and he was about to look for a cross and garlic.
The reason I decided to tell that little bit is that you said "I play a part in this as well." Of course you do, but the best way to know exactly what part is to be around new, healthy people--and learn from them. There are lots of ways. I chose store owners, because it was a thread-like connection. I wouldn't be expected to socialize. It was safe and I learned a lot with just that one step. I learned what I could say and couldn't say to healthy people. I already knew that my ex found fault with what I said and put me down, but now I knew that decent people wouldn't do that for saying exactly the same.
It helped me disengage without requiring major change and to see that I was more ok than I thought.