Devastated in Watching Life Fly By

On the 19th we had to put my dog Penny down. She was only 4yrs old. I’ve had her since she was about 6 weeks old. I rescued her from under a truck on a rainy spring day at my old job. She was dropped there, terrified and soaked.
She was snuggly, sweet but timid. She protected me fiercely from strangers and animals in our yard. She loved to nap with me and snuggle in my bed. She enjoyed being outside playing with Bo and Chloe. She hated water, loud noises and thunderstorms made her a bit nervous. If she was in trouble, she’d sit in the basement till she was sweet talked out. She made a funny barking/howling noise to talk to us when she missed us, was excited, or wanted to eat.
She did not adjust to having Chloe in the house. She loved my pregnant belly and would follow Chloe’s heartbeat/movement across my belly. She’d stay right next to Chloe as an infant and nap with her on the bed, couch or next to her in my arms. As Chloe became older and louder, Penny became nervous. She went after Chloe when Chloe was a little toddler. She thought Chloe’s snack cup was hers because it was on the floor and ran at Chloe, growling. I screamed and she ran and sat in the basement for hours. We attempted to re-home her to an adult only family or a rescue for American Bulldogs, but nobody would take her. “We are full.” We gated Chloe and Penny apart during meals and even cooking. I took Chloe to the bathroom with me or to do laundry for 6 months or more. Finally Penny began allowing Chloe to hug her, to kiss her, to pet her at free will with no side glance, no stiff posture. We relaxed.
On Monday I was cleaning out the pantry in the kitchen. Chloe was in the kitchen doorway talking to me when Penny walked up behind her from the living room. Chloe turned to see which dog it was and most likely let her pass. Penny lunged at Chloe’s face with such force Chloe was knocked over hard. I screamed, Chloe screamed, Penny stood a foot away. I grabbed Chloe and she had a tooth mark on the bridge of her nose and above her left eyebrow. No blood, no medical attention needed, just hugs, a snuggle and love. I dragged Penny to the basement and had to put her in a crate because she refused to stay there. I kept telling her it was not okay. I was shaking. She seemed defiant. I text Mike at work and told him she had to go that night, no exception, not to let me change my mind. Mike came home hours later, asked us to go get him coffee from Dunkin Donuts and to take a ride. I went to the basement and said goodbye, sobbing. We did. Penny was gone when we returned. I told Chloe a man took her to a new home because he wanted a dog and really needed a Penny. I’m still a sobbing mess. Chloe cries on and off for her. Bo wanders the house and yard crying a few times a day. Mike is quiet but tears pool up whenever something reminds him of her. We LOVE her fiercely just as she loved us. We just couldn’t choose our dog over our child. She’s been trained, she’s been examined, she’s been given chances. She had to be put down. My dog is dead. Mike’s is here. I’m angry, jealous and hurt. I’ve never had to put a dog/cat down for a non-medical, non-old age reason. I never thought I would need to but after years in a vets office, years seeing terrible bites, a friend with over 250 stitches in her face from a family pet, I could not risk it. My daughter comes first. My dog is gone but never forgotten. I’m destroyed.