Not invalid, just incorrect.
The quit claim deed listed both my brother and his wife, while just my name appeared with (single) behind it
Is this not how title was held before you sold it to your brother and his wife? If no, you need to file a deed correcting this error.
Where does the law stand with regard to my husband being omitted, property sold without his knowledge,
Why would you sell property w/o hubby's knowledge? If not from a legal standpoint, then from the standpoint of a fair and equitable union between two people in that any major decisions - like this sale - would be discussed first. Legally speaking, if he was on title and you conveyed property w/o including his name on the deed, he would still own his 50% share in the property (provided there's no one else on title not mentioned in the original post.)
Papers were prepared and signed in a rush.
BIG mistake. MAJOR mistake. In fact, that was just plain stupid. Rushing into any real estate transaction with no one to monitor the situation in your best interest can open you up to liabilities civil and even criminal.
I was still in the hospital recovering from a head injury
All the more reason NOT to rush. Were you on medication when you signed the deed?
and assumed all was on the up and up.
Has no one ever told you that to assume simply makes an
ass out of
u m e?