Help With Episode

I saw this when I was younger and need help to find out which episode this is.

What I remember its about a kind man who thinks he is too kind and people step upon him etc.

So I think, dont remember but think he gives up his soul or something so he could not feel anything and thus become stronger.But instead turns into demon.

His humanity is saved by his little dog who returns to him when all others left or he gotten rid of them.

Anyone remembers which episode this is?

Thanks in advance.