Hi Sun,
I related to many of the things you said, and while I don’t have the answers, I can tell you a bit about my FOO. It sounds like we have a similar family dynamic, so maybe you can find some connection?
I was the target child, and have always been sentimental and hyper-sensitive. I don’t know why. I cry over everything. A happy movie that’s emotional will make me bawl like a baby. I have very few of my childhood possessions, as NM disposed of them all, but the few items I do have, I cling to. Small gifts from my grandmother are my greatest treasures. Even though I am now estranged from my co-Father, who hurt me badly, I still have ticket stubs to concerts he took me to as a child, and am sentimental over those few happy moments where I thought, even for an hour, that he loved me. NM and co-father caused irreparable psychological damage, yet I am still sentimental over the handful of happy moments that I DID have. My entire life, people have told me to stop being so sensitive. It’s not something I can turn off.
My sister, like yours, is a mini-me of my N-mother who catered to her every whim until the day she died. After N-mother passed, my sister became even more cold and heartless. She is an ice queen, filled with nothing but anger. Loves no one but herself.
My brother was the golden child. He too has become very cold and detached, but it wasn’t always that way. When he was a child, he was pushed to be the overachiever that NM demanded him to be. He was forced into competition ice skating, becoming a child actor, even forced to convert to Judaism because NM said “Jews control the industry.” He was painfully shy, had no friends, and was the most sensitive kid on earth. This lasted until his late 20s, when he married an N, just like his mother. After that, he became cold and cynical. Just like your own brother, he claims to have forgotten the life he had before marrying his N-wife. He started treating me badly, and we finally ceased contact.
I also wonder how we could have grown up in the same household and ended up so differently. I will say this. Even though I am the most emotionally damaged of the three, I am by far the best person, and I think you are too. What may seem like a character flaw is perhaps something we should be proud of. We are sentimental because we are compassionate people who have love in our hearts. We are the ones who should be angry, but it didn’t turn out that way. Why we didn’t, is anyone’s guess.