Make a decision that your health and well-being are your single most important asset, and begin living your life to protect it. Take a personal stand that this is not the way you want to live, and this is not the behavior you want to role model for your children. Here are a few suggestions to get you started.
One should never assume that it's impossible to slow down, or that by doing so, someone is going to shame you for it. Learning to stay focused isn't going to lead you to less work, but it will certainly help you to manage stress, allow you to do more, and generally provide a smoother working experience.
Do you ever feel you've been busy all day and didn't get much done? You may not have realized it at the time but you were likely multitasking all day; helping co-workers and clients, switching from task to task, responding to email, phone calls, knocks on your office door, being pulled into meetings.