Hi Reddit, this is my first post and this one is longer than it was intended to be.

Okay so story time, also, a PSA that English is not my first language so please bear with me.

My younger sister Lucy (19F) and I (22F) currently live in a two-bedroom apartment that I pay for. Since starting work, I’ve taken responsibility for Lucy to ease our parents’ burden—they’re focused on our four younger brothers (16, 11, 10, and 7). Lucy is in her first year of uni and does part-time work to help where she can.

After graduating from uni, I was unemployed and was job hunting for 4 months and used my savings for our rent, so our aunt Martha (mum's second cousin) offered to accommodate us for the time being. I thought that was so generous as it will help us to save money. Every week, I still contributed to buying groceries, paying for power bill and the family car's gas, just to show appreciation so it can seem that my sister and I are contributing something while there and not living there for free. Plus, whenever our dad visited from our hometown once every month, he always gave Aunt Martha a generous amount of money to cover food and utilities for MONTHS. But she would blow it all on gambling within a few days, then start indirectly complaining about food and power running out faster than usual.

In our culture (Pacific islanders), we support extended family through contributions for birthdays, graduations, fundraisers, and events. So, when my cousin turned 22 in January, Lucy and I contributed what was asked in the family group chat (with Aunt Martha, Aunt Mary, and six of our cousin sisters 26, 24, 22, 21, 19 and 17). This was when we already moved out to our current place, but me being the people pleaser that i WAS, I went out of my way to prepare all the salads for the party—potato salad, coleslaw, egg salad, chicken salad, and fruit salad after I finished from work. I even paid for all the ingredients and was up until 5 a.m. prepping everything, barely rested before the actual celebration. Guess where the initial budget of the salads went? Gambling.

Now fast forward to Lucy’s 20th birthday. It was on a Saturday. We had already moved out and didn’t want to bother anyone or make them feel obligated to contribute. Aunt Martha insisted I post in the group chat, so I did—but I specifically said no monetary contributions were needed, just help with decorations and food prep. They all agreed and reassured me they’d help.

But come the day of the party, no one showed up. I got home from work at around 5 p.m. to find Lucy and her best friend already cooking. No texts. No calls from them. Nothing. I felt horrible—she shouldn’t have had to lift a finger on her birthday. I called my only 2 friends to help out, and we pulled things together. The party turned out great and Lucy loved it, which was all that mattered. But not one of them apologized or even acknowledged ditching us. Since then, we haven’t spoken to any of them.

About 2 weeks ago, Aunt Martha messaged the group again asking for contributions for her younger daughter Stacey’s 18th birthday. The amount requested was triple the usual, because she wanted it to be "grand." All the family members paid and contributed. I didn’t. I told them I won’t be contributing to a family that’s clearly one-sided and only shows up when it benefits them.

Now my phone’s blowing up—relatives calling me petty, selfish, saying I’m bitter about a teenager's milestone. Martha aka the gambling addict, is now guilt-tripping me, saying Lucy and I “leeched” off them when we stayed there and did not contribute shit. I told them all to go, make a big circle and fuck themselves. They’ve even taken it to Facebook and even dragged my mom into it. She’s now asking me to reconsider. Lucy says she’s feeling bad too and wants to contribute, but I told her to start growing a backbone and learn to say no.

Side note: this isn't the first time this has happened, and I have had enough. So, Reddit AITA?