Need To Unload

So its been 15 years since my mother has been to a movie in theatres.  I have a few extra bucks, and Joey is out of town and so is Marlow so I invite my mother to a movie....my treat.  I also invite my big brother as he and I go to movies often together.
WELL.
First my older sister snap shows that she wasn't invited.  Do you want to come?  NO! Im broke!  I never have any fucking money! Ok, so I KNEW this so I didn't invite her.  She makes a big scene and upsets our mum before she EVEN leaves the house.
Then, I lend my mum $20 to get a phone card, no biggie.  We go to the movie, which my sister didn't know my brother was going to and threw another shit fit....screaming so loudly at my mum on the phone that we could ALL hear her.  In the end we lied and said he went with a pal and we just met up on accident.  To which she sends me some stupid text saying that she never feels wanted.
Mind you, I have invited her over before but she doesn't want to come when I have kids in the house and that's til 7pm on week nights.  On weekends she's always too 'busy.'  When I go to her and moms place she hides in the basement.
Anyways, she then demands mom bring her coffee.  And because I can't stand to see my mum have to go home and deal with all the crap my sister pukes out I leant her another $10 to get java.
So now she's on this tirade how we never do anything for her.  FIRST, this is the first time I have ever invited any family member along where I pay.  SECOND, I try to draw her out but she always has excuses and never returns the invites.  THIRD, her attitude is atrocious and embarassing. She once yelled at a Tim Hortons cashier because the ice in her iced coffee didnt push against the lid therefore they were ripping her off.  FOURTH, she has all sorts of people after her and I don't want to be involved in that shit.