A few things that might help about triggering mean behaviour:
- Often "just asking questions" is used by trolls to trigger arguments or pull people into debates. That's why when you use that language people get immediately aggressive online. Try asking for where or how you can learn more instead, it's more genuine and let's other people feel like they won't be obligated to argue later.
- "Why don't you just" type questions can come off as dismissing all the thought that went into something. If you rephrase to learning more about a topic you can often avoid that.
- Don't be afraid to walk away from online discussions that hurt your feelings. It's okay to apologize and clarify, or leave a response not answered if you're in an argument online. There are a lot of angry/grumpy people who are happy to lash out when you give them a chance. They don't reflect most people in the world, they're just very over represented online.
I think also as you get older you will learn more about yourself and build up some confidence to shield your feelings. It's valid to feel hurt, but over time you learn which things matter and which do not.