I feel like I've fucked up my relationship with my nephew, he's only 5 years old but he's a tall kid for his age.
I tried teaching him to read and ended up getting pretty frustrated at him and he's avoided me since then. I don't think he's told his mom but I still feel like an asshole.
Is there some way i can fix it. I feel awful.
You could try to apologize by admitting you were wrong to snap at him, and make it clear you have no intentions of harming him.
Not sure why you decided to include the fact that he's tall for his age tho...