Yeah, I found that CBT isn't 'deep' enough to uproot problems, just helps you handle them a bit better (but not actually solving them).
Maybe try the diary again. Even if you don't feel like it, make it a daily habit to open and write sth. Even if it is 'I don't want to write anything' or just one word, anything. I think it keeps that sort of 'portal' open and your voice doesn't get completely muffled by the thoughts or indeed tiredness..

But I can assure you you haven't failed life! You can't fail life. And it's a good thing you can't face dying! And it has nothing to do with cowardice. How I see this - being a complete outsider - is that you're locked in a position where you know what you want to do, you want to live, but sth blocks you....But I do believe you want to live. The reason death appeals - I think - is because life seems too much of a hassle to be worth the trouble, or indeed seems even as black and empty as death. But life is mobile and ever-changing opposed to death and even though you 'can't' live right now, this is bound to change, and that is a fact. So, try to believe in life and in your will to live. And try to find things you love..Even if they're 'stupid' little things and you think it's stupid thinking of it..Just make statements like 'I love the clouds'. I realise how Disney-like and even 'stupid' this may sound but love is indeed everything for me!

So..Much love from a stranger and I hope you feel better soon