You're not stupid....you're human. And he's only claiming that you're cold hearted because if you're acting like he isn't sick and like you don't care then he think's he's losing control and losing his comfort zone and will say anything to drag you back in.
I actually am starting to find it quite amusing when he starts. I switch off now and I get the "you're so cold" line quite alot, but it makes me laugh.
Once you see the pattern you can predict what they'll say next and it amuses me.
I'm coming around to thinking I'd rather be the "cold hearted selfish b***h" than the codie sucker....but that's just me. I'm not actually the cold hearted selfish B yet, but I sure do wish I was!!