I feel ya. My dog is sleeping next to me now and I cant imagine not having her. I got her from the pound when she was 3 months old. She changed my life - I went from being a complete lazy ass to going for a few walks a week - then running - now I bike with her and she runs by my side and I lift weights every other day. Last week she ran 12 miles and averaged over 13 mph including potty breaks. She has gone 10+ miles at a time.
I do everything I can to keep her healthy and hopefully give her the best and longest life possible. I run her outside and she has her own treadmill for bad weather, take her to the dog park, take her for car rides as often as possible, I give her good food with omega fats, supplement with extra virgin olive oil, brush her teeth, keep her at a healthy weight. My vet always comments that she is the healthiest / best kept dog that he has seen in 20+ years of practice.
Sometimes I will think about her dying and I will cry. She is the best dog that I will ever have, I know that I will be devistated. I feel for you, ill give my pooch a hug for you tonight.