Omg.. Are you me? Because I'm going through the same damn thing with my older brother but the thing is my grandparents whom I live with complain about it but never actually does anything about it.
Just say that yet you're still busy taking care of family and doing chores in the house....unlike someone. You're just taking a rest and you deserve that. She should mind her own business and use that energy on finding job instead.
Tell that to her face.
I think she just frustrated of herself so she vent it to you. If I were you I will ignore her. Don't think about it too much.

I know this is not the right site to ask question about family/relatives problems but it's making me insane!!!
So I have this female cousin in her 30's w/o a job since birth as in no job history. And whenever she sees me doing things like watching TV or taking a nap she keeps on nagging on how useless I was in the house even tho I sometimes do the cooking and taking care of my mom who just survived cancer or my niece who is special. Compare to her who just eat,gadgets,sleep,repeat. I mean I'm no college graduate has no job at the moment but still...
I don't know what to do or say to her every time she say stuff. She is older than me by 10yrs. So I can't just say hurtful stuff and even if I do others are gonna say I have no rights to do that.. It's so frustrating.. This has been going for 3yrs ever since I stop college due to financial problems. Urrhhhh....