Hi Mandy...
Well unfortunately I didn't have a choice about the therapy after having my son at 22 I was mis diagnosed and aggressively treated for it or I should say mis treated, made me very very sick.
I basically lost all my 20's.
So I wouldn't consider having therapy in my 20's.
By the time I hit my 30's I had major marital problems.
And I'm now I'm divorced (happily)
Just I haven't really started "real therapy yet" is my point, but hopefully I'm getting there.
Enough about me.
As far as my friend I'm sure there are some differences, but your story did seem very familiar to me.
My friend and her sister were very close in age though and I think that set the stage for even futher problems.
The younger sister looked up to her older sister and never could understand why her older sister could do the kinds of things she did.
The older sister was gorgeous, smart and just plain fierce. Oddly enough she was very protective of her sister to outsiders though, but would do some pretty mean things to her as well. She would taunt her. I think this stemmed from a few things
One being a very dysfunctional upbrining and two a very low self esteem.
I felt very badly for my friend because at times she would not see it coming and it would often times be something very hurtful.
Now the answers to your last questions.
The older sister is married with 3 kids and has a successful husband with a business etc. She still has a ton of emotional problems though.
They still maintain the same relationship the 2 sisters. The younger one does so much for the older one. The older sister I should mention though will do nice things for the younger one, but at times...this mean streak comes out when you least expect it...knocking down the other.
What's sad and difficult is they are close and because of that the older one uses that to her advantage. She knows her weakness and uses that whenever she wants and like I said she can be fierce.
I just saw my g/f the other day and she was explaining a situation her sister was taunting her about this guy that it didn't work out. She is (single).
My g/f said I feel like when i was a kid and it's like your in the yard getting your "pony tail pulled". and it's my own sister.
Oddly enough her brother is my ex husband. Her and I maintained our friendship, which I'm thankful for cuz I had a very messy marriage at the end.
I grew up with her and her sister.
Anyways sorry if i rambled.
If I can help in any way pm me anytime.
I hope that I did somewhere in there...lol.
Take care

Eva