[header] How to cope when your sibling gets cancer [title] Talk to your support network. [step] When things feel overwhelming, reach out to your friends or family. Find someone that you can lean on, and ask them, " is it alright if i call you or come over when i feel like i need some support? " [substeps] Talk to your support network openly and honestly. 
Let your conversations with them be a safe space where you can work on your own feelings without judgement. If possible, try to lean on someone who isn't too close to your sibling.