Dealing with an "Invisible" Disability

Hi.  I've posted many times; just an update for those unfamiliar with my situation. I've been married almost 30 years.  My husband was diagnosed with ADHD within the past two or three years.  He also has been treated for depression since he was a teenager and for anxiety.  He has been fired from two jobs and has a very difficult time getting new jobs. (He's not looking now despite weekly visits to a vocational rehabilitation counselor and my heartfelt pleas that he actively search for employment.)  My husband is getting paid currently by his parents, with whom he spends three or four days a week, helping out.  I work part-time, with my work consisting of almost 30 hours per week for one employer and freelance jobs that I do at home.  

This summer, our two adult children are at home.  The children provide some help around the house although not as much as would be ideal.  My husband does almost none of the "visible" housework (that is, things apparent to me or the children or guests; he does work on the cars, fill the little swimming pool in the backyard, and make an effort at keeping his bedroom, which used to be our bedroom, clean).  I'm very tired and very stressed and staying in the marriage only because of finances at this point.  The children are aware of tension between my husband and me and are aware that their dad does not pitch in much but I'm not sure they know why.

Finally, my question:  What do you say to other people about why your life is falling apart and how do you ask for help, when one of the reasons is that you're married to someone with an invisible disability like ADHD (and in this situation, its companions anxiety and depression)?  I don't want to embarrass him or reveal too much but yet, I hate to live dishonestly.  Thank you.