Angi, I think the hardest thing in loving a pet is deciding when "we" can let go. I have been in your shoes many times and each one was just as hard. When I could let go and start the grieving process...it was much easier. My heart goes out to you and your family. One day that 12 year old will be standing in your shoes and he will have to explain to his child what is best. Don't be too hard on yourself...cherish the memories of your Lab and think of him as you continue to walk the trails. He will be with you in spirit....