Dealing with finance-related frustrations

I just finished filling out my child's college financial aid application.  My husband used to do the taxes and financial aid applications, but this year, I took over these chores because of my husband's ADHD.  Doing these things causes me a great deal of anxiety because of our financial situation (husband is chronically underemployed and not looking for work), but I'm committed to getting the job done.  So, first, my husband suggested not including all his income on the tax forms (he works for his dad part-time as a caregiver).  I said that I was going to put down the income, because as his spouse, I could be held liable for his cheating on taxes.  Then, today, I discovered that my husband might have greatly underreported a certain number last year, thus making it look as though we did something shady with our money this year.  I am very stressed by this. 

I'm sure that I'll figure out some resolution.  But it is very disheartening to me that my spouse tries to cheat like this.  Do other people have ADHD spouses who do stuff like this?  To add to this, we can't talk about finances.  I mean, we can, but my husband always says that talking about these issues makes him feel guilty, defensive, and too aware of his inadequacies.  So, I take that as a form of "off-the-table-itis," meaning a response that effectively makes a topic impossible to discuss. 

I'd appreciate any thoughts people have about the issue of evading the law (and also some sympathy, if you can spare a bit; I don't usually ask for anything but I'm really depressed now).