Bbj, it sucks that he is still trying to make you feel guilty for his actions. Dan is a "serial cheater" and excuse me if that sounds harsh but it is the truth. Your "lack of interest" towards his business/dream is just a poor excuse. His choices are HIS choices only. Dont take the blame for any of it. Personally I find it cheap that he puts you in he position to explain and apologise for "not being there" with him after all this time you have been standing for him and your marriage. He knows better, he is just trying to feel better himself.
I dont know what you have decided to do, I would still give you the same advice:distance yourself and dont be a part of his life only the way he wants you to be. xxx K