Co-signed for a loan in 1997

I co-signed for one of my husband's friends; a student loan in 1997. We soon found out the guy was a criminal and had used his 6 children to get sympathy from other gullible idiots like my husband (and I for signed for a stranger!!) to give him money.
It was for $5,000 and we knew he would not pay and when he didn't show up for classes we asked Citibank if there was anything we could do to get out of it and they said no.
I've divorced the husband since then and my lawyer told me to just ignore creditors and not pay it...It's up to $11,000 now. My credit is otherwise flawless and I was able to purchase my 1st home with my new husband...
Now I'm getting letters from creditors that they plan to sue me for this old debt.
If the guy was a real friend, or if it was my debt I would have gladly paid it off ages ago...But this guy makes it his job to rip off innocent people and I refuse to pay this...he may be in jail or dead, I don't know. I don't keep in contact with my X because he was abusive and the relationship ended badly.
Can they put a lien on our new house now?
Thanks for any advice.