Am i a really bad friend?

Oh my goodness. If you have this much to complain about, then you have answered your own question. You are feeling used because you are being used. It is good that you are able to to put your foot down and tell her no, but I hate that you feel the need to ask if your refusal makes you a bad friend. Your refusal makes you a friend who will not be walked all over. Unless you are happy with your arrangement, it is time to surround yourself with different 30 year old friends. This woman has shown you exactly what she is about. Recognize her for what she is and accept it or move on