I think my cat is depressed

Hi all! I’ve had my baby girl tuxedo cat for almost 12 years now, but she’s probably around 14 (we adopted her online and there was no info on her birthday). She’s so sweet, she really helped me with my depression since 2020. She never really cared about me until around that point. She’s very very skittish, I’m talking like if you even clear your throat around her she’ll run away. She chooses her people carefully, she only likes my dad and I.

Since 2020, she mostly slept with me in my bed by my head. It was my favorite part of every day, being able to cuddle with her. Lately, I’m lucky if I get a snuggle once a month. We got a new cat in 2023, and don’t get me wrong, I love her so much. She’s the opposite of my first cat, she’s energetic and playful. She doesn’t react to loud noises and lets us pick her up in every which way. She’s so silly and entertaining, and I don’t regret adopting her at all. However, I feel like maybe my first cat is jealous of her? Can cats even feel jealous? They don’t really get along, sometimes I’ll catch them sleeping in the same bed but that’s about it. I told my parents we should wait until my first cat passes but my mom really wanted a cat that liked her. Again, I love this cat to death and wouldn’t change a thing but it might be important to note.

She stopped bathing herself a while ago. Everyone’s been chalking it up to old age. We gave her a bath recently (she hated it) because she was just so gross and it helped, but barely. She stopped using the litter box, she refuses to use it. She now only uses pee pads that I have to keep in MY room… and at first she was just peeing on anything. My dad’s bed, my clothes, the rugs, etc.

I’m freshly 18 and my parents don’t seem concerned at all. They mostly don’t want to spend the money. I’m just so worried. I want my babies last years to be filled with joy and warmth, she deserves it. Does anyone know how I can help? Is there medicine? Is it just her getting old? Thanks!