Do you get frustrated with friends?

I have this friend. She's sort of my best friend. I can't say she's my best friend because she kind of ties for that position with another friend that I've known since forever, but she is a VERY close friend.

This friend of mine is a doormat for her entire rather large extended family. She is one of 7 adult children, the youngest of whom is nearly 40. She has her own little family that includes her two girls and her hubby. She is the ONLY person in that entire family who does anything for anyone. As a matter of fact, she does EVERYthing for EVERYone. And none of them are ever willing to help her with anything. And she gets annoyed with them and stressed out, but still won't say no to them.

In the meantime, I can see the negative effect it has on her girls and her husband. A little over two years ago, her sister took it upon herself to move herself in, along with her newborn twins and her deadbeat abusive boyfriend. Since the day they were born, the twins have become my friend's full-time job. No kidding. Even when the sister is there, she (the sister) does practically nothing -this laziness extends from actually caring for the babies she so desperately wanted, to housework, cooking, laundry, etc. Not only that, but she has never paid a dime toward rent, food, babysitting, utilities, the several loans my friend and her husband have taken out to get her a used car, storage shed, etc. The deadbeat boyfriend eventually moved out, but he never paid either -not even child support. Whenever my friend's sister got her hands on any money, she used it for a membership at Curves (not diapers and milk, but something for herself) or diet pills. She continually takes off in my friends truck and returns hours and hours later with no explanation of where she's been, no phone call, and an empty gas tank. AND? She doesn't even mention the empty tank, so my friend has actually run out of gas on the way to pick her own children up from school. My friend and her husband have used up their girls' college fund, are behind on all of their payments -including house and car and OBVIOUSLY, her husband is very frustrated. The sister runs the house -she tells them where they can park in their yard (actually stepped out into the yard the other day to tell the husband that he was parked in HER spot), what television programs they can watch, and screams at my friend's daughters and husband all of the time. The sister has been working for months and has yet to pay a dime toward ANY of the expenses.

The girls -my friends daughters, who are also my goddaughters, are depressed -anyone can see it. The youngest has taken to reverting to baby-like behavior, the oldest is sullen and withdrawn and I know it's because Mom has no time for them. Meanwhile, they're in debt, the house needs multiple repairs that fall into the DIY category, but none of my friend's family is willing to help her husband accomplish the jobs.

On top of all of that, she's the only person in her family (eventhough her two brothers LIVE WITH her parents) that can repair things at her mother's, program the cable box, hook up TVs, put together armoires, chauffeur, her parents and brother to and from doctor's appointments, and break up fights between her parents (sometimes physical fights).

And I get frustrated when my friend cannot take 15 minutes to talk to me on the phone because she's feeding the twins -at 6PM, when their mother is home (or should be) doing nothing productive.

I have talked to my friend on a limited basis, but it doesn't seem to get through to her. She's doing serious damage to her children and her marriage. I don't want to be too pushy about it, because I'd hate to lose a friend, but I just don't understand why she won't help herself.

Does anyone else have experience with a friend like this? Any suggestions?