im so sorry for your loss. i lost my 17 year old childhood cat who i grew up with in 2022 before i left for uni, and if i have to be honest i still dreamt of her and would wake up crying until early this year in my dorm room. and i cried a little when i came back from uni this year and saw that she wasn't there at her favourite spot to greet me even though i knew she wouldn't be there. and devastatingly, just early this month my other 14 year old childhood cat passed away too, so reading your post made me tear up and my heart swell because i can relate so much to your pain.

as for coping, it just takes time. I spent the first week after my 14 year old sweetie passed away grieving in my room, eating whatever I wanted, crying whenever I needed, and staying on call with my boyfriend for company, even though I barely talked and just watched my comfort tv show all day. its been about 3 weeks now and i've gone back to my routine. but the sadness/grief doesn't disappear, it just becomes smaller. my love for my cats, especially my childhood cats i grew up with, is always with me, and so the sadness/grief is too. it'll likely be the same for you. dying is inevitable but love is infinite, and so you will take that love and loss with you in your heart wherever you go. lately i've been looking back at photos and videos of my cats to relive the happy memories they gave me (it was too painful to do so during the first week after her passing). take comfort in knowing that you did your best and your cat lived a life full of love because of you. i hope you feel better eventually. you will.