Thank you everyone who has given me advice.

by the way, I can’t type in chines at work. My sister and I are Chinese. Her husband is a foreigner: believing in spending boosts economy. I am actually younger.  Her husband used to have a decent job but they both had no idea about budgeting. I was told there were serious consequences every time when she borrowed money. Anyhow, I will lend her money: about 80%, instead of 100% of what she asked so that I will not have a sense of guilt for not lending them. Thanks again for your advice.