4 months postpartum and had to put our dog down

My husband and I have two dogs, 9 and 7 years old. They are like family to us. Yesterday our 7 year old lab was acting off and he took her to the emergency vet. After doing some tests the vet told him she likely had an undetectable tumor in her heart that had burst and fluid was leaking into her heart and abdomen. Even if we had tried to help her it would’ve been extremely temporary and likely extended her suffering. We decided to humanely euthanize her. I’m a FTM to a 4 month old. I’ve been dealing with PPA and PPD which I’ve started therapy for. My daughter has MSPI and was colicky for the first 3 months of her life. During that time my husband and I had some frustration with our dogs. It had gotten much better but I feel so guilty now. I wish I could go back and not get frustrated with her. My house feels so empty. She loved food more than anything and I was so excited for my daughter to sit in her high chair trying food with our sweet lab sitting on the ground waiting for things to drop. Now we’ll never get to experience that.