How do you explain not mourning the dead?

I recently lost my oldest brother.  He lived in the streets for 20 plus years so the person I knew growing up I have not known for the past 30 years.  We were not close and he died in another state which no one realized he was there. Several of the family members want to do a memorial but I will not attend.  Dare I say I have done my own mourning and a memorial is not something I can attend for my own personal reasons.   Growing up for both of us was difficult because he was my mothers oldest and I was my fathers.  He did not move in with us until he was 9 after living with our maternal grandmother.  I really think he hated that we had a family and he was not part of it.  I could say so much but it would get to messy and upset my family if I wrote the truth.   I will just say my brother never had a true relationship with anyone unless he could get something out of it.  I have cried but it is not because I will miss him.  I cried because I thought the life he lived was sad and it did not have to be.