I feel like I've failed my dog

Our great pyr mix Ginger was 13 years old when she was PTS and I feel like I've failed her. Sorry if this post is all over the place, I just feel like I need to get this out. A bit of background, she was a Great Pyr, Akbash, and Anatolian mix and she had hypothyroidism all her life and she was on 2 types of pain pills for her arthritis. Saturday night we had a Halloween party that our friends were hosting. Before we left she started trembling but not enough to be concerned about, it was a bit chilly. She had moments when she wouldn't feel great and then would perk back up again. When we got home after the party she took a few steps off her bed to come see us and then laid down and did not get back up again. We had to bring her bed over and lift her onto it so we could bring her into bed and her breathing was a bit off. She seemed better Sunday and my bf's lovely mom who is a vet tech came over to check her over because we couldn't afford an emergency vet visit. We all thought she would get over this and we could get her a vet app on Monday.

Sunday night into Monday morning was the worst. I think she's been having something internal going on because as we were in bed, bf was already asleep for a couple hours, Ginny was just panting so hard and struggling to breath and restless and was hunching her back and sucking in her belly while laying down. She is such a stoic dog so for her to be showing pain it had to be agony. We ended up taking her to the emergency vet in the middle of the night to be put down because she was suffering so much and it couldn't wait and we didn't want her to suffer anymore. My sweet girl was in agony because I couldn't do anything over the weekend. We're planning on having her cremated so we had to leave her body in the room and it was the hardest thing. I finally paid for her cremation today and I feel bad but I keep ignoring their phone calls. I can't talk about her without bawling. It's taken me a couple days to write this out.

She went downhill so bad in 24 hours and we don't even know what happened to her. I miss her so much and I feel horrible that her last day was so bad. I am not okay