I had a cat named Cala from ages 6-22. She meant the world to me. When I was at my worst and wanted to die she was the only love I knew I had. I do believe many times she kept me alive.
Her kidneys started failing. She was a wreck, peeing everywhere, in pain, weak, stopped being able to walk. She meant more to me than anything. But I had to let her go. Her living helped me. But living was torture for her.
Haylee is never "just a dog". She's so much more than that, just like my Cala was more than a just a cat. So it's not stupid that this affects you and is hard for you and it's not stupid that you're tormented about it. But honor the fact that she means so much to you and accept that when and if she gets to that point...if it is indeed soon...she's trusting you to be able to make the decision that stops her pain.
And that's probably all stuff you didn't need to hear and doesn't help. I just wanted you to know I've been there and your having to think about this option does not lessen at all what she's given to you and what she means to you.