How do you handle family members who ask for handouts?

I now say no. My sister is always in need and btw she is a BSRN and makes good money. My 1st husband and I paid off 20k in debt for her, let her live with us for free and he got her a car financed through his credit union because her credit was terrible. She never paid the monthly car payments to him and we ended up paying for her car. We considered this a one time handout. And she laid low until the car was paid for. About 15 years later she hit rock bottom again and had a teenager. I let them live with me rent free for 1 year so she could save money to start over. She didn’t. My husband and I divorced and she was a big part of the reason. I am now happily remarried to a wonderful man whom my sister consistently insults. Last year, she stole what little money my mother had from her bank account. We didn’t know until the assisted living facility told me my mom was going to be evicted for not paying 3 months rent. We paid cash to catch up my mother’s rent and other bills. My sister took out a credit card in my mother’s name as well. We paid that and cut off all banking access for my sister to mom’s bank. All my mother gets is social security and a $500/month pension. My sister stole my mail, took it to the bank and told them her purse hand been stolen and the mail was all she had to prove that she was me. They gave her a debit card and once again she emptied mom’s account. She took no responsibility for any of this. Now, she’s asking me for rent money. She claims the IRS has done a wage garnishment of her pay. I’m sure this is true. But, I believe she probably owes a great deal of money to the IRS. Even if I were to pay her rent this month it would go on forever. I am not going to pay her rent. I feel terrible about her situation but she has consistently over spent and made bad decisions. I have lived well within my means and have invested well. I’m now close to age 67 retirement and also had a medical situation that rendered me completely blind for the past year- I couldn’t work and didn’t claim disability. She never physically helped me or my retired husband during this time. I now have sight in 1 eye and am awaiting a cornea transplant in the other eye. My husband says if she moves in he is moving out. I will not let her move in with me a 3rd time and have probably freely given her around 60k-70k over the past 27 years. I still feel guilty because I don’t want to see her suffer or be homeless. Why do I feel so bad?