If you ex-spouse's attorney and ex-spouse represented that your ex-spouse still owned the house, it is not unusual that your attorney relied upon their representations. If this is what happened, the problem here isn't that your attorney committed malpractice; in my opinion, he or she did not. Rather, the problem is that your ex-spouse (and possibly his attorney) committed fraud. You should hire an attorney to file a motion to address this issue as soon as possible.
If, on the other hand, you are saying that your attorney had information in his/her file that showed that your ex-spouse no longer had the house and your attorney didn't catch that there was a problem and recommended that you go ahead and sign the fraudulent divorce paperwork, then you may very well have a case for legal malpractice against your attorney as well.
A fraud can be grounds to modify a judgment of divorce. You should consult with a qualified family law attorney. You should act quickly since there are time limits that may bar your ability to bring this matter back before the judge if not timely pursued.
Of course, this is not meant as legal advice nor does it establish any professional relationship.
I urge you to talk to a lawyer. The first issue is whether or not there was any equity in your home at the time of the divorce. If your home had no equity and was underwater so to speak then if your husband bailed it out and saved it from foreclosure that would not impact you. If you are still on the mortgage it would help you. Again, more information is needed and you should definitely talk to a lawyer. Good luck to you.
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