Birth Brother died help

Hello Im a 32 yo adoptee born in the UK, I was one of seven and three of us were put up for adoption. My adoptive family moved to Australia when I was 4, my birth family all resided in UK. 3 years ago me and my bio sister .(who were reunited when I was 18) found our brother who we visited in Prison, I got to spend one mere hour with him, I then had to go back to Australia. My sister called me and told me David our brother died he was 37, he had been hit by a car crossing a roundabout. Ive never felt grief like this is my life, I feel ripped off, i feel guilty I should of wrote more, made more of an effort. When we met David, the previous year I had returned to the UK to meet family, which I found through facebook. With my brother Jamie, he was one of the 4 hour who were kept, and their lives were horrendous, poverty, my mum with addiction died when they were pre teens, My second oldest brother (also called david) committed suicide a year after my mum died. My other brother Alex last we knew of was in a psyciatrct prison. My sister Nicole I met only once, she was lovely we bonded, after one meet she no longer wanted anything to do with . My brother John died as a baby, of SIDS..though ive always had my doubts that maybe something dodgy happened with John. So before David who has just passed I faced alot of reunion let down, I emotionally cut off , when I met david , I was trying to keep myself safe so much, that I didnt try forming a relationship, and now hes dead im devestated, its brought up so many emotions. Anyone had simular experiences? Sorry if it dosent make sense my story sometimes read like a jerry springer episode.