@DJ - thoughts are with you and your fam'.
I know the feeling. Had to put down our family dog way back in 2000. He was with me through various stages of life - great dog. All the way from elementary school into a few years of college. Passed around 13.5yo. Black lab - severe respiratory issues got him in the end. He was struggling. One of our family friends helped us with the process. He worked for the SPCA & came along with us for the final walk down by a river / creek, and then to have the dog put down and cremated. We then went for a walk at one of his favorite trails later in the year and planted a small tree in his honor and spread his ashes there and near a walking bridge over a creek.
That dog was something. He could run for hours & then go for an ocean or lake swim. Hell ... even had him chasing after the soccer ball during the '94 World Cup as he watched our enthusiasm, lol. He even kicked that thing a few times.