How can I prevent disappointing my mum (45F) or myself (26F)?

My relationship with my mom hasn’t always been great, but we’ve grown closer as I’ve entered adulthood. For some background, my parents divorced when I was two, and I primarily lived with my dad. My mom remarried and had two kids (a 16-year-old son and a 13-year-old daughter), but that marriage ended three years ago, and she’s struggled to adjust to being a single mother. As a result, she’s been reaching out to me more, even though I’m living independently and managing my own life. She also deals with a disability and is facing increasing financial difficulty. Recently, she asked if I would join her and my siblings on a vacation next summer. To be honest, I’m not keen on going. She sees this as a crucial opportunity, since starting in 2026, her income will significantly drop, and she’s worried that my brother might not want to participate in family vacations anymore as he transitions into adulthood. I’ve always found it hard to say no, as I don’t want to disappoint her, but I feel that I’ve reached an age where family vacations aren’t a priority for me anymore. My friends are eager to travel together, I want to spend time with my partner, and I have limited vacation days and budget to consider. Plus, I prefer to travel during the school holidays when prices are lower. In summary, I’m uncertain about whether I should go on this family vacation and how to communicate my decision if I choose not to. (For additional context: Both of us have ADHD, and I’m also autistic. Our family has a history of mental health challenges, which can make social interactions a bit difficult.)