This has been one hundred percent my own experience. It's often very difficult to decide what to do. I think the reason that the decision to "leave" brings such relief is that it puts an end to the torturous limbo we are in while we are waiting for the path to be clear.
Even though we don't have a crystal ball to see the ULTIMATE outcome, we know we've made a significant step toward caring for ourselves, for a change. And getting on the road to freedom makes us stronger with every step.
Be prepared for little freak-outs from time to time--the first time you have to deal with something big you're used to sharing with him, or times when you might feel a little lonely and start second-guessing yourself. When they hit, post here. Those feelings WILL pass, if you give them a chance to. Maybe they won't happen, but if they do, it's perfectly normal and it doesn't mean you've made the wrong decision--remember that.
Hugs!!