This is a really tough question.
We're not experts, but we can certainly relate to how frustrating it is when people don't hear what we have to say, or when they invalidate our struggles. This might be more about parents being in denial, rather than being unloving or unsupportive. This doesn't excuse their words or actions, but perhaps in their worldview and prevailing attitudes of their time, sometimes children can be seen as a measure of their "success" as a parent. So to see their child struggle is a personal failure.
It isn't easy changing their mindsets, but one thing we can perhaps shift is our view of them -- that they do not intend to be hurtful and are also struggling themselves. In the meantime, we hope you're able to get support and emotional validation from other sources like siblings, friends, or school teachers and counsellors.