I'm going to treat my stepfather like he doesn't exist
What makes you want to treat your stepfather like that?
Because he doesn't do anything to me, I'm just tired of seeing him around.
If you hate your stepdad, the first thing you should do is ask yourself why you hate them. Sit down and talk to him you can both be on the same page.
His body makes me sad.
It's not nice to judge people based on how they look. If his body makes you that uncomfortable, maybe you can suggest working out together to help him get in better shape. That way you can get to know him more, and help him be healthier.