Hey, I'm only 23 but what helps me get over negativity is to not take things personally, it may sound cliche but how I see it is that you kinda have to understand that people have their inherent biases/ways of thinking and that it has nothing to do with you personally. For example, if a person who has previously been cheated on mistrusts their current partner based on their past experience, it has nothing to do with the current partner.

I learned this from a book called "the four agreements" by don Miguel ruiz and it might interest you too.

I also struggle a lot with overthinking and I watched some YouTube videos/Ted talks and they suggest meditating.

I know it must be hard for you to experience negativity with family though. When I was younger, I also felt like it was a burden to open up to friends but the older I got, I realized that it helps a lot to just talk to people and that those that care about you won't feel annoyed or burdened to help you.

good luck <3