What is the proper response to "I can't do anything right"

I do not know how to answer this. After every ADD moment my husband says "i can't do anything right" and normally i respond with something like "it's not a big deal, don't do that to yourself, it's not your fault"

But what about when he does do something wrong? How do I respond then?

Scenario- Husband withdrew money from our checking account. Not a big deal, except he didn't go to one of our banks ATM's so there was a $3.99 fee for the ATM plus the $2 fee from our bank. Now 6 dollars isn't that big of a deal, but I'm unemployed, so it matters. He noticed the additional $2 fee this morning and gave me the "i just can't get anything right" sob story. I pretended i didn't hear him, b/c in this instance, he screwed up! I just couldn't bring myself to say to him "better luck next time" etc. I was angry!

Then I got mad at myself because I was angry at him for doing something he 'forgot'. It's just so frustrating. I don't feel like i can get mad at him when he does things like this, b/c I know he's not doing them on purpose, it's his add brain letting him forget. But seriously! how many times do I have to tell him the same thing!

How as a spouse are we supposed to deal with this?