My life stopped one month ago...

I lost my little Asya, my pekingese dog, she was 16 years old, blind and deaf, and with arthritis problems, sometimes she took pain medicine but we were able to settle everything, I was completely devoted to making her last years as comfortable as possible: I cooked for her, gave her glucosamine and chondroitin supplements, she was still loving, eating, snoring in her sleep, and making funny noises when she dreamed... She was old, and she had difficulty walking, but I carried her everywhere, gave her massages and looked after her like she was my baby, I slept with her and held her in my arms every night to make her feel safe.... and had her in my mind all the time...
One month ago, I was out, and when I came home I found her smothered with tv and lamp cords, I dont know how she did that, she somehow embroiled herself in this cords and in panic she must have rotate over and over, and I was not there to save her.... I am so horrified and anguished thinking about her last minutes, I cannot get this out of my mind and am eating myself with so much guilt I cannot breath...
And still, after one month, I hate myself and I am immersed in self-loathing - I almost convinced mayself I am such a terrible person, because I let my dog down, I wasn't there to save her, and nothing matters any more.... I cannot think of anything good I did for her, I remember only the moments I was busy, I was not home, I was in a hurry, I was nervous, like all of these 16 happy years never happened... Will this ever stop? Is this normal?
I am not very good in english, and I cannot write anymore, I cry all the time... there is nothing left to say.... maybe we must believe what others say ..... that we gave our dogs everything and when its time to go nothing can stop it.... maybe the time passing will make things better.... I just cannot believe this right now.... as much people tell me its not my fault, I feel more and more smitten by guilt...