For a man your age this is not unusual. But the persistence of the condition, even in the face of powerful incentives to behave otherwise, may indicate something more. I would agree with others on the forum that seeking professional medical/psychological advice may be an alternative.
You mention that you have a pretty good job. Do they offer an employee assistance program? These can often be low-cost opportunities for consultation with a professional. If you feel confident in their promises of confidentiality, you may wish to pursue that. But in any case, do something, and make sure your wife knows you are doing something. She may react very positively to the fact that you're recognizing the problem and taking affirmative steps to deal with it.
I've been around ADHD for a long time. Some of the symptoms you describe sound very familiar. I would encourage you to see a psychologist first. They have several tests that they can administer that will help them understand what may be going on. But also a word of caution, ADHD is often something diagnosed right away. ADHD should be a default diagnosis, meaning all other possibilities should be eliminated first.
Good luck to you, and stay as far away from the military as you can. Your lack of focus would be extremely dangerous to you and to your fellow soldiers/sailors/airmen/marines. If you think you're having trouble coping with what this problem is doing to your family, imagine the problem if your actions/inactions injured or killed another soldier.
Get help, tell your wife you're seeking help, and do everything you can to keep your family together. No one can replace you in your child's life.