Get a seperation agreement in place as soon as. Get all your financial paperwork, savings, pensions together and head to a lawyer. Don't move out until that's sorted. It may seem civil but once houses and money involved it can go sour very quickly.
Be honest with the kids, they're about the age mine were when I left. That they are loved beyond any doubt and make sure they know that. Get a stable routine in place for shared care, the best outcomes are kids who maintain regular contact with both parents.
People looking in will speculate and don't be surprised if some chose a 'side'.
Drop me a pm any time.