You can't blame yourself. You did what you thought was best. And even if you had done something differently, you don't know if it would have changed the outcome or not. When my beloved cockatiel died suddenly, I tortured myself with asking myself what did I miss, what if I had gotten up an hour earlier, etc. But it doesn't really do any good going through all the what ifs. Just try to take comfort in knowing your bird had a good life with you and that he was well loved.