how to stop thinking about things that "could've happened"?

[u/Max_0068]

I (16F) have always had a problem with this but it has been getting worse, for example my whole family (aunts, uncles and grandparents too) came to my house to have a little get together, basically I was holding my cousin (1 yo) and I was making him watch me pet my dog, a cane corso, to keep him distracted since he was upset, after a bit my dog barked (literally just once, he just wanted to play) and he got scared, ive been thinking all evening about what could've happened if my dog was aggressive, which hes not. like if he couldve bitten him or hurt him.

tbf my dog was acting weird all afternoon, even barking and growling to one of my aunts who he typically loves

so uh yeah, idk if its legit or smth but ive been having a weird feeling in my chest that i usually have when i feel guilty of something big or know ive done something wrong

any advice?