I need opinions

So throuout 2023 and most of this year me and my grandma haven't gotten along and it's gotten so bad that I thought about running away. Now that my grandpa is moving away on my birthday I'd have to stay here and I won't ever get to see my mom or other family unless I feel really guilty about it. My 18th birthday is coming up Saturday and I plan to officially step back for a while but I don't know how to tell her or if I should. I might just end up taking my documents and leaving with the bare minimum. It's so hard to tell her anything that I'd rather just do it without anyone knowing-. I don't know if what I am doing is right and I wanted to get people's opinions on it.