Hi, I'd like to help you with your question.
It sounds like your husband is still involved with his ex. No one needs that much time to discuss issues about children. He is using his children to make excuses for his behavior. He has not let go of this relationship and continues to keep it going by visiting frequently and staying.
If your husband will not pay attention to how you feel about his relationship with his ex, then he has no intention of changing. You can try asking him to attend therapy with you to work this issue out. To find a therapist, ask your doctor for a referral. Or search on line at http://therapists.psychologytoday.com/rms/.
If he will not go, you should go yourself. You need the support right now to decide how to respond to your husband's behavior.
You also may want to consider a trial separation. This would give you time to see how you feel about continuing the relationship. It would also let you see if he is taking your marriage seriously or if it continues to be one sided like it is now. Sometimes, trial separations help spur the other person into paying attention to the issues of the marriage. Here are some resources to help you:
Should I Stay Or Go? : How Controlled Separation (CS) Can Save Your Marriage by Lee Raffel
Should I Stay or Should I Go?: A Guide to Knowing if Your Relationship Can--and Should--be Saved by Lundy Bancroft and JAC Patrissi
If your husband and son will not share in helping you around the house and you have tried talking to them about it, then you may need to stop doing their work. Allow them to do their own clothes, make their own dinner and clean certain areas of the house themselves. When they run out of clothes or go hungry, they may rethink the situation.
I hope this has helped you,Kate