What to do about mooching sister?

Oh gosh where do I start? My older sister (48 years old) has been living with me for about 7 months. She had this mid-life crisis of some sort and decided to move. To accomadate her, I moved into a bigger apt. I was thinking that she would get over her mid-life crisis and become a productive member of society; self sufficient; since she has been doing that up until 7 months ago. She did find a job but it doesn't pay much. She barely gives me $200 a month, which does nothing but make up the difference from my old rent. Their is still food to buy, water bill, electricity, etc.

I really want to help her, but it doesn't seem that she wants to help herself. I feel as though she reverted back into being a kid and expects me to take care of her like I do with my two girls. She doesn't know how to manage her money. She sees me keeping my appearance up, for instance, me getting my hair and nails done. She'll want to do the same thing but she can't afford it making her being unbearable to be around. Every once and awhile she'll go get her nails done but then she runs out of money to buy her much needed diabetes medication.

I swear she is like my 3rd child. She'll even ask me to make her doctors appt. Sometimes I think that my own kids will grow up, move out and she will still be living with me. How do I get rid of this canker sore of a sister? I tried to be tactful, but that just caused her to get depressed and go into this thing that nobody loves her.