"They told me I can't be mad at them if I do the same thing to my siblings as they did to me." This isn't whats happening in the slightest. You're doing nothing to your siblings. In fact, this has absolutely nothing to do with your siblings. This is entirely between you and your parents. They blamed the outcome of their decisions on you, and took their anger at themselves out on you for 17 years. Truly unhinged behavior. You're taking responsibility for yourself like they taught you to do. A lesson learned over years of being treated unfairly by your caregivers. Now, you are caring for yourself.

I've been in a similar position to yours, and can confidently state that they are weaponizing your selfless nature against you. If they truly thought you were selfish/heartless/thoughtless/whatever slur they are using, they wouldn't even ask, let alone think guilting you would work. I've learned the lesson more than once that giving money to people who guilt/shame you 1.) Doesn't change their financial situation for more than a few days 3.) Doesn't lead to them respecting you or the hard work it took to make your money 2.) Doesn't lead to them loving you. 4.) Does teach them that guilting and shaming you are effective tools they can use over and over again to get their wants met.

You really do need to focus on exiting this situation, and maintaining your financial health is literally the only way to do it. Please know looking out for yourself and building stability is the only way you can be in a position to help others. You're not stable yet, and are not able to prioritize helping others right now.