My mom took back her blessing after I got into a fully funded master's abroad, and I'm unsure if going would be wrong

Assalamu alaikum, here’s what’s going on. I’m a sister who just finished university. Before graduation, my sister asked if I’d go abroad with her son so he can study while I do my master’s in the same country. I wasn’t sure at first-I’d just graduated and wanted to start working, build my career, and finally be financially independent. Money has always been a touchy subject because my parents make me feel guilty about it, even though they do support me. They act like we’re struggling, but our lifestyle says otherwise, so I’ve always felt this weight to become self-sufficient. Anyway, my sister offered to pay for everything-tuition, housing, all the big costs except my personal spending, which is fair. At first I thought I’d be putting my career on hold for her son, but then it hit me: this is a huge blessing. A free master’s degree? Only a fool would say no. So I agreed. We planned everything for months before I officially graduated. When I got my certificate, we went to my parents for their blessing, about half a year before applying. They were fine with it-basically said “if we’re not paying, do what you want.” We did tell them we’d need them to cover my daily expenses, and they were okay with it, even encouraging. They worried a bit about me handling life in a new country, but they didn’t refuse. We talked about them visiting and everything, so I thought we were all good. Months went by. I was busy applying, sorting papers, and giving my parents small updates. Some family stuff came up that distracted everyone. Then suddenly, my dad calls my sister and says I can’t go unless my mom comes with me-and my sister has to pay for her visa and all. Keep in mind, my mom has some difficult traits, and she and my sister aren’t close. My sister got upset, telling him, “Isn’t it enough I’m paying for your daughter’s tuition?” And honestly, I get it-they’ve sent other siblings abroad and paid for everything fully. But when my sister helps me get the same chance they gave my siblings, it’s a problem? It feels really selfish. A couple more months pass, and today I got the email: I’m officially accepted! I was overjoyed and told my parents right away. But my mom just looked at me and said, “I’ve decided I don’t give my blessing, and if you go, I won’t even visit you.” They totally flipped, acting like they never agreed or supported me. As if those months of planning never happened. I asked why she didn’t say this before, and she avoided the question. When I asked for reasons, all she said was that I’m not responsible-even though she knows I am. I’ve proved it many times. What hurts most? They didn’t even congratulate me. No “masha’Allah” or “we’re proud of you.” Nothing. I got into a master’s program I’m not paying for, and my own parents basically threatened me. I’m torn-would it be wrong to go without her blessing?