Old topic, but I experienced the same, so I completely understand.

Shame

Feeling wird

Dissapoinment

Unlucky

Feeling cursed by ill fate

Depression

Hopelessnes

How

Lacking normal family for whole your life
Lacking family support for whole your life
Isolation

I experienced the same. Im only normal person in family of four people, two siblings, as you wrote, at early 20 becomed personality disrupted and their mental heath is worsening, along with parents, which were normal when I was born but appareantly among few years they developed abusive and neglective tendencies, and their mental health is also worse every single year. They started to abuse and neglect even themselfs, no hygiene, food malnutrition.
Both sibling living with them, one of them, as you say, exploiting parents financially and enotionally over 10 years, lazy, do not want to work, paranoid, psychotic, threating with suicide. Do not want to visit psychiatrist. Parents blindly supporting her financially.

Sometimes, on photos we were normal family as others family, nice smiling mother, who loved her motherhood and proud father. Our home was tidy, there was enough of food.

Now it is four abusive tyrants, dirty home, mess everywhere, trauma to live there even a day.

I know that stupud melancholic feeling its eberything lost and you will never have normal family as other. You are alone living with sick people.

Its weird. I was not exception. In early 20, I started abuse drugs to deal with pain, and after time, I get mental breakdown and I had to visit psychiatrist. There was psychotic mentall illnese geneticaly in our family genetics.
I was taking medicine for while and get through ppschotherapy. Im healthy now.

This is reality. I was only mwmber of family who was able to take responsibility of my own psychological health. Parents was born into small rural areas with deep stigma of mentall illneses, so it is “shame” for them to admit their problems. They would probably rather pick death than to visit mental health worker. They have sad future along with siblings.

But its their responsibility. I feel sad for them sometimes. Not for them, but for family we used to be sometimes and fact, this is gone, this parents are gone, this siblings with once I was friend are gone.

Life is shit sometimes, for some people. There is lot of people in extened family who are like me, normal, healthy, friendly, but we are just in superficial contact. They are not in close contact with this family. No visitors did not come here for decades. Our family is shame for all family generation.

I totally understand you how it is like to be only normal person in whole family. Althought its rare, you are not alone. There are more like us, I believe. They simply move out from family, I think, if it is possible to start a new life, find healthy people, maybe have own healthy family which brings them joy.

You are not obligated to be their saviour because of few stupid shared genes. You are not expected to nothing. You are just expected to care about yourself and make yourself happy and that is your priority.

Life can bring out sad things really.

I believe in you.
I think you must be strong person, me, either everybody who remained resilient despite that horrible conditions.

I heard, that sometimes, strongest ones face struggles. Weak people have smooth lifes, strong ones face hardships because they are empowered to handle them. Take it as compliment. I do not know any wise strong or conciouss person who had easy life.