We have been together since 1997, divorce 10 years later, but still togther, I'm still living with him, he doesn't want me to leave,
But why is it so hard to leave someone that you love so much? And want to be with, but you know that there is no chance in this world that you'll never remarrie,
Is it cause I don't have another place to go?
Is it cause I don't have a car?
But I'm so very much in love with my ex and he says that he stills loves me too. And he wants me around

Mostly because you are in your comfort zone... You are used to it. Something new as in walking away introduces you to the unknown... and the unpredictable.

Same reason some people are hesitant to walk away from a bad relationship.

You use to each other, and know each others moves, and moods, very well, so of course, it hard to move on, and being with each other everyday, does not help at all.