ADHD partner not interested in parenting tasks

I recently finished reading "The ADHD Effect on Marriage" and have been searching the forums as well to learn more about ADHD and parenting.  I haven't found a similar experience to mine, so maybe it has little to do with ADHD, but I'll put it out there in the hopes someone has dealt with it and found some solutions.

My husband has not been formerly diagnosed with ADHD, but has all the symptoms and his childhood report cards certainly show he has had them for a while.  He functions extremely well though - has kept an excellent full time job for over 15 years, very careful with finances (though paying bills has become my job since we got married - he tends to lose paperwork) and has lots of tricks to ensure he is never late for appointments, meetings, etc.

The problems in our marriage started when our first child was born 3 years ago.  It really bothered my husband when our son cried (which he didn't do all that much - he wasn't a colicky baby) and he had little patience for spending time with a baby.  However, it wasn't too difficult for me to do most of the caregiving for our son, even after I went back to my full time job when he was a year old.  I did find most of my free time and hobbies starting to disappear though.

My husband really wanted a second child though I wasn't sure we could handle it, but when my husband seemed to get more involved when our son was 2, we got pregnant again and now have a 5 month old.  A few months before our daughter was born, my husband's stress level seemed to skyrocket (more drinking, smoking again).  Now, things are really difficult.  My husband does not have the patience for things like waiting for our son to use the potty before a meal or bath time.  Our son has really started backsliding in his potty training because of this (starting to want to be in diapers all the time again).  My husband also does not have the patience to sit at the table while my son and I finish eating.  He eats quickly and heads off to the TV room, while I sit with my son (and our 5 month old in her bouncer chair) until he is done.  My son is starting to think if he doesn't feel like eating he can just leave the table, and tried to do this at his grandparents place, much to their surprise..  My husband rarely holds our daughter and will only spend time with our son if it is in front of the TV.  I have taken to doing both of their bedtimes, which can be a real balancing act.

So my question:  Is this level of disinterest normal for someone with ADHD?  And are their tricks to get him more tuned into parenting?  I am worried about the long term effects this may have on our kids and frankly, I am also exhausted.