Finding comfort after my beloved cat's passing

As-salamu alaykum, dear brothers and sisters. I recently lost my 15-year-old cat, and I've been finding it really hard to cope. My prayers have become especially difficult. My cat used to sit quietly beside me during Salah, and when I'd finish, he'd come right onto my lap as I made dua. It was our little daily habit. Now, praying just fills me with sadness-I often start crying and lose track of which raka'ah I'm on. I miss him so much during these moments. I keep wondering, is there a dua I can say so that, insha'Allah, we might be together in Jannah? I worry about forgetting him there or that we'd want different things in the Hereafter. I also feel like I failed him. Allah blessed me with such a wonderful companion, alhamdulillah, but his last few months were tough. He had some health problems, and even after visiting several vets, we never got a clear answer. He passed so suddenly, and I can't stop thinking, 'What if I had done more?' I know we shouldn't dwell on these thoughts, but it's hard. We took him for a vet visit that afternoon and brought him home around 9 pm after he received some oxygen. But by 10 pm, he was struggling to breathe and passed away. We tried to arrange an oxygen cylinder at home and get him to an emergency vet, but it all happened so fast. I didn't perform CPR or rush him out again, thinking it was his time and Allah had called him back, but now I feel guilty for not trying harder. Any advice or reminders of comforting duas would mean a lot. Jazakum Allahu khayran.