I still get the constant internal chatter but it's a lot less intense than it used to be. When you're in the thick of the JW routine, mixing in JW social circles, with JW family, you have sources of irritation on many levels (i.e. the mindset and beliefs) which set off all that mental chatter.
When it was at its worst, I found it helpful to do something enjoyable and entirely different that would put the brain on 'idle' for a while. Walks in the park, messing about with the kids, reading a novel, watching silly tv, going to a movie - anything distracting that helped temporarily shut out the cacophony and jumble in my head. It's OK not to have the answers immediately. It's OK not to know where you stand on issues. It's OK just to take a break and enjoy the simple pleasures of everyday life.
When I would start to feel shaky because I was no longer in the JW box on so many issues (being 3rd gen., there's a life-time of conditioning to overcome), I'd mentally focus on one thing only: 'Jerusalem did not fall in 607, therefore the Org's not what it claims to be, therefore it's open season on all of their teachings.' Pick your own deal-breaker issue and repeat internally as necessary when things get overwhelming.