My two older sisters are best-friends, and i'm their third wheel.

My eldest sister (51y) has six years on me. The middle one is (47y) two years older. The middle sister and I have never gotten along. A sibling rivalry instigated by my Mother's full blown alcoholism. The eldest left home at 17. Then around four years later and around 17, the middle sister moved in with the eldest.
My sister's have been the best of friends for 25+ years as far as I can tell.
I was Invited to my sister's fifth marriage. Middle Sis was made of honor. It was my first time wedding/reception coordinator JOB!. I spent $2000.00 and worked from 5AM-12AM. My brother and sister-in-law were renewing their vows at 9AM the next day. It didn't take long to realize how badly I got screwed by my sister. She needed someone to work prepping the church and tending to incidentals at reception. I barely got to eat any dinner of drink (water), which was medically necessary.

In March of last year my middle sister's house was in foreclose and she was about to be fired for violating a patient's privacy. Sometime that spring my sisters arranged a trip to Ireland together. We are all pure Irish. Only I was not invited. However I was asked to take the middle sister to the airport and pick her up.
I agreed. Till the humiliation, pain and anger set in. I give her two weeks to find another driver.
Some time pasted and I was asked to pick the middle one at the dentist office. She wanted to get some lunch. After five + drinks and prescription pain medication from the dentist. I got her home so she could drink some more.
I received a call from the next morning that either I or her friend left the back gate open, and one of her dogs got out the following AM and was hit by a car and killed.

I broke off contact with my sisters. I fed up with being their gopher, driver, maid, all around punching bag.

I do not see a relationship of any kind, at all with my sisters.
Does anyone have a different opinion?