Am I a selfish sister?

My sister C is borrowing me money. I remember me and her husband are also working and he recently got his salary from his 21 day job and I never even saw what they bought from it. I also paid his husband for repairing our house so he got extra money. I told my sister C my sister J who is in large debt is asking me money borrowing me also money so Im gonna lend her some money just for now then my sister C asked me to borrow money as well I told her I cannot promise I'll lend her money because I have so many things to spend it too bills and my adoptive parents are asking me to buy them new mattress as well. They know my salary is on day 25 so they bug me when its 25 asking to borrow some money am I a selfish sister?
Am I a selfish sister?
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