If you were paralyzed would you want to go on living?

my cousin got shot in the back a year ago & he is paralyzed from the chest down,he is a former marine that served in afghanistan & basicly he got a medal that dont mean a thing..my cousin was a teriffic athlete that was part of the varsity football & wrestling teams..he was so in shape that he use to be able to kick my azz..he had a gorgeous girlfriend that was supposably waiting for him...but when news got back that he was crippled in this b/s war my cousins only friends is his family...my cousin has asked me a few times to give him a tail injection that he wont wake up from...I feel his pain but im not the one to take his life...he has become obnoxious & verbally violent with everybody..it hurts me just to even visit him because he asks me evrytime to end his life...how should i respond to my cousins wishes & what is the right thing to do?