I can only tell you how I felt (or how I remember how I felt). I knew that people loved me, I knew that people valued me but it just didn't register. All I could hear were the internal voices telling me it was all over and in the long run it'd be better for everyone if I were gone and at least I wouldn't be in pain any more.
It's totally irrational stuff and you block out any and all positive stuff because it's not what your mind (my bipolar mind in my case, I don't know what Graham specifically had, there are many different shit flavours of this disease) wants to hear.
I'm not being overly dramatic when I say it was a toss of a coin, more than once. Now I know now in the cold light of day, when I've got the right medication, the right mindset, the right lifestyle, the right behaviours and the right company around me, how awful it would have been if I'd done it. The ultimate permanent solution to a temporary problem. But living with it is absolute hell, I can promise you.
His family seem vocal in hoping that some good can come out of such a tragedy, that people who are struggling go and seek help, which takes incredible strength on their part.