I know this is strange to say on The Fandom Website, but if engaging in fandom is genuinely stressing you out and making your mental health worse, then you can take a step back! If you still want to see the fan stuff, become a lurker, if even that's too much, just disengage altogether
I know it can be tough, it's natural to want to share in your joy of a thing with other people, and the Internet makes that easier than ever, but it can also make it near impossible to actually enjoy things.
If you find yourself getting twisted up in the morals of liking a certain media you may find yourself unable to enjoy anything at all, out of fear that the creator will be revealed to be a bad person. It does happen, yes, but more often than not, it's just people exaggerating to farm engagement. I think you'll find that, if you look hard enough, you can make yourself believe anyone is a bad person, when most of the time it's just them fumbling through life trying to figure things out.
Especially if you're a pre-teen or teenager, I wouldn't recommend engaging with fandoms beyond lurking. The truth is, that fandoms are full of people just wanting to pick fights and get a laugh out of other people's misery, and especially in a highly emotional and hormonal time in your life, you become an easy target. I used to watch video essays quite frequently, and I just saw it happen again, and again, and again. Where someone around 14-17 gets popular, and they make a normal teenager mistake, and get instantly harassed off the Internet.
Of course I can't actually tell you what to do and that's just a suggestion, despite what people may believe, teenagers are capable of choosing things for themselves, and that's often what it takes to learn how to be an adult. I just ask that not just teenagers, but also anyone who may have any mental illness or disorders that affect how you feel about morality, be careful when engaging with fandom spaces (especially fandoms of popular media) and step back if you start to feel stressed out about it.
I'm not exactly good at this myself lol, it's something that takes time to figure out. But so long as you pay attention to what's making you feel bad and figure out how to remove or handle it, I think it's something you can become good at.
In an increasingly online and lonely world, it's tempting to participate in everything, but while humans are social creatures, I don't think we were meant to be this social. Sometimes it's better to keep your circle small, and only venture out into the wider world on occasion when you make need a quick reality check.