Assuming you truly have the desire to change things and that you actually want help, here is some unsolicited advice: go into individual therapy for yourself and if possible try to start couple's therapy too. Look for long-term once-a-week therapy and don't be afraid to shop around for therapists because it's important that you like the person.

If that seems too daunting, order The Emotionally Abusive Relationship by Beverly Engel or get it out of the library. It's a good starting point and in general books written by therapists are a great complement to therapy.

http://www.amazon.com/Emotionally-Abusive-Relationship-Abuse...

If not for yourself, do this for your children, who suffer as much as you - if only because you and your wife are so important to them - but are helpless to change the situation.