That’s about one of the hardest decisions you can possibly make, I’m glad you’re looking out for her and helping her not suffer, but I’m so sorry for what you’re going through. Had to do this with my dog a year ago and it was really hard. If you can, try to think about how much less she’ll be suffering. My dog had a hard time breathing for a week or two, no animal should have to suffer like that. I was happy in a way that he was comfortable in his last moments, being held by his family.
Grief is a complicated thing, there are stages to it just like with a human. I broke down trying to write this actually, it’s been a while since I’d thought about my dog like this. You’ll always miss them but it does get easier. Getting a stone or planting a tree to memorialize them helps a lot. I go to my dog’s stone whenever I’m home and say hi to him, talk to him in my head you know. I think it helps