I love my family, but they are treating me like a bank! How do I stop them from asking to borrow money all the time??

**sigh**

I love my family, I really do. But they are not very responsible with their finances. My sister is living beyond her means because her rent and household expenses far exceed her income. My uncle-I don't know what he does with his money. He doesn't pay rent where he's living, and he doesn't have a car, so I'm not sure what his story is. They are constantly asking to borrow money- $25 here, $200 there, and they swear it's for bills, or cough meds (that was my uncle's last excuse!!). I'm sick and tired of it. I'm not a bank. I am an unmarried mom with a toddler. I need to make sure my daughter's needs are met before these two grown people. I have a little money saved that I received from a life insurance policy my mom left me, and I get ssdi for a disability. I can't squander that money on loans to family members!

How do I politely tell them that I can't lend them anymore money? I don't want to hurt feelings. My sister always lets me stay with her when my tot and I come to visit, and my uncle (who lives there) always cooks for us. I'm not sure how to say what I want to say without hurting feelings.

Any advice?