... generally not made decisions based on myself or what I wanted. I don't mean that to sound as if I'm refusing to take responsibility, I accept those were my choices. Only they weren't, it never ever occured to me to even think whether or not I wanted to.
This is a tough nut to work thru, Tups. Not impossible, though...
I've been there too. And sometimes, not nearly as often now - but still sometimes - I'll find myself there again - and later kick myself for not standing up for myself, or deciding to choose differently or not being brave enough to try to hang with other people, while being my own self. That's part of the risk in connecting with others now, for me. And the connections are damned important, so I continue to put myself in those situations and give myself another chance to "do something different than I usually do". I'm making progress, but I am still anxious about it.
As for how this happened and responsibility:
Well, my take on this is that it really wasn't a choice for some of us. Not for me, at least. To survive - have food, clothing, shelter (the external basics of being "cared for") - I had to master the ability to live in two different realities. (no wonder - I felt I never had enough space or time!!) The topsy-turvy insane world of my Nmom AND the one the rest of us live in. To protect what little Self I had, I had to master mind-reading all her moods, predict what would/wouldn't set her off into her "Mr. Hyde" mentality. To have the APPEARANCE of a normal connection, normal relationship... I had to twist myself into a contortion of dysfunction that was both a safe hiding place - and also "armor" against the sometimes unpredictable times when I would become a target - for no reason at all.
Like prisoners who develop Stockholm Syndrome - children of emotionally abusive parents (or mentally ill parents) - develop personality traits that seem to indicate that one is in sympathy with the imprisoner; even like the imprisoner... to avoid even worse experiences or being targeted for evil. And sometimes, long after we are free from that situation, in fact... sometimes we continue that protective cloaking device (please.... please let me be invisible!) and even believe that it our self.
It is NOT our self. And though we accept responsibility for who we are - how we are - how can we be responsible for doing the "unthinkable" (denying our real selves) to survive? If you saw a child doing exactly the same thing - how could you blame that child? You couldn't, I think. And so we learn compassion for ourselves... and begin to forgive ourselves the betrayals of our Self for swallowing our self-respect, our own wants and wishes, even our own selves (in my case)... simply because we wanted to survive or connect or be recognized as "mattering" - having our needs met (validation).
The good news is that I did survive, long enough to finally figure out how I was "hoodwinked" out of myself. The good news is you survived too, Tups - all of us here have survived and have the opportunity and ability to figure out the "trick"... and we still have NOW, TODAY to put our Selves right, to create order from chaos, to finally resolve all the old emotions that couldn't even be known to ourselves while we were physically at the mercy of the "imprisoner". NOW is SAFE...
Now, we can protect ourselves through choices, personal responsibility, and we have the luxury to feel all those emotions that we would have - if we'd truly had a choice when we were smaller & younger. It does take awhile to process all those years of emotions - and not all of them are pleasant - but each emotion makes your real Self - more REAL.
At least: that's how it worked for me. Your mileage may vary!

HUGS to you... you've had a huge breakthrough insight... so treat yourself kindly, give yourself time to adjust, give yourself some "slack" while you sort out what's what... and feel free to give those weeds hell! You'll have the prettiest garden in the neighborhood!