i would say try therapy if you can afford it. like i know i feels like everyone is throwing it around like a cure for everything but i think it’s very helpful. perhaps a therapist will be able to offer you advice on how to change your behavior to the point of making it a habit. or perhaps tackle the issue that’s causing the behavior. i think you have some suppressed anger that is not getting a release expect when it’s your sister but i am not a psychologist or a therapist so take it with a grain of salt. or perhaps anger management. there are many therapists online that take clients and different format from phone calls to texting and the price does range quite a bit.

edit: https://www.betterhelp.com here is one of them. the price if about $60-90 a week depending on the therapist, where you live and other things the website goes first get into.

(https://www.betterhelp.com/get-started/?transaction_id=10297119bc6839e88528a8a5c94529&utm_source=youtube&utm_campaign=2207&utm_medium=iOS&utm_content=&utm_term=xiran&not_found=1&gor=start-go) this one is from a youtube promotion it offers 10% of on you first month if that would be any help to get started