A little bit of background:
I'm the youngest person in my family with two older sisters. The younger of the two sisters, who is the middle child and is now 21, has always had some... problems. Things like being held back in school and having trouble making friends. Things escalated when she got into high school and went from being this really sweet, shy kid to basically being a teenage bimbo. She also started stealing money from our family, like taking my mom's credit card and spending thousands of dollars on clothes and then denying it. My family has had pretty serious money problems ever since our father left and so her spending was a bigger problem than it might be for a well off family. She has always stolen things, like when we were much younger and my mom bought me some special type of candy and it mysteriously disappeared and she finally admitted two weeks later that she had taken it after much accusing from yours truly.
In addition to stealing large sums of money, so much so that now my mom has to hide all of her cash and credit cards when my sister comes home (she's at college), she is almost completely unbearable to talk to or hang around with. By this I mean she is basically completely disrespectful and selfish, but basically only with her family. When she's with her friends she acts pretty similarly but they tolerate her for... whatever reason. My eldest sister has a pretty serious boyfriend and they might be getting married and he's basically expressed that if they do get married he doesn't want the middle sister to be in their family's life at all. She has never shown any remorse for what she's done to our family and even through a brief stint in therapy (we can't afford much more or else we'd have her going to a therapist, and since she's over 18 my mom can't force her to go to one) she still acts the same way. We've always attributed it to having seriiiiiious middle-child-syndrome, but today my mom found out that my sister stole 15 Adderall pills from her which my mom needs since she has extremely bad ADD and has to work like 14 hour days. My mom basically said to me that she's thinking about cutting my sister off entirely and telling her that she can't come into the house and she wants to know if I agree with her. I've had to deal with being "man of the house" since I was really young due to my dad leaving, but this is something which I'm completely at a loss as to what to say. I mean, I can't stand my sister and I know that she's harming our family but the thought of not having her at Christmas dinner or never seeing her is a pretty scary thing. Basically what I want to know is what would you do if you were in this situation? I hope I've given enough information for someone to make a reasonable decision, but I just don't see where we can go from here apart from spending a ton of money on therapy. If anyone else has had to deal with something like this I'd really appreciate any input. Thanks.
Edit: I forgot to add that any type of intervention is completely useless. If you try and sit her down to talk to her then she literally starts yelling and saying that she doesn't want to hear what you have to say and will storm out of the room. The few times where we've gotten her to listen to what we have to say it didn't seem like she took it in at all.
Posts
Anyway, maybe if you do cut her off she'll figure it out eventually. Seems like she does whatever the hell she wants and continues to do so because she thinks she can get away with it. Show her she can't treat you guys like that.
Your sister has emotional problems as bad or worse. Sociopath, kleptomaniac, chronic liar...we can throw those around, but most of us aren't licensed mental health professionals, so we can only conclude that you must cut her off for everyone's sake, including hers. You cannot force her to get help short of some kind of wacky court order, and that probably isn't a viable option (I'm not a lawyer any more than I am a psychiatrist); it seems and feels awful to disown a family member, but it sounds like you already know you really, really, really have no choice. Do it, and don't let her beg her way back into your good graces, or things will go right back to shit or worse. Best of luck.
Tell her to get out and stay away.
Yeah, she's not acting as a family member. You will only be able to treat her as one for so long. It seems like that time has long since past.