Mums diagnosis of metastatic RCC

My mum has been diagnosed with metastatic renal cell carcinoma. I’ve done a lot of research about this type of cancer and what happens when it spreads and types of treatment. The consultant told us it was incurable and that treatment would only prolong life. 

The cancer has spread to lymph nodes and lungs and have noticed over the past week or so that my moms cough is getting worse and she’s becoming tired everyday. Going out shoppping and things is taking its toll on her and she’s sleeping a lot through the day now. I’m an only child and have very minimal family support. We are waiting for a referral to oncology to discuss treatments. But I’m struggling to come to terms with this and seeing her deteriorating and not being able to help her. We lost my dad 14 years ago to a heart attack, my moms mom died with lung cancer 14 years ago so no immediate family are around. 

Just wondering how other people have came to terms with things and if they’ve been a carer for someone with cancer how have they managed this because I genuinely feel like my head is constantly mashed. I’m mentally exhausted.