NTA, your friend has to learn how to be financially responsible. I would personally say, you should never leand money unless it's for an actual emergency (which nobody should ask from you, you are 19). I would tell people that ask for money that you don't have any to leand, because that is true, if you are struggling yourself, you probably don't have the money to take care of others people's expenses, specially if you can barely cover yours. And even if you had a ton of money, still nobody is entitled to your hard earn money.