Sorry to hear you find yourself in this situation. It goes beyond real estate--you need someone to advise you on the relationship status--most likely an attorney. I currently have a client in the same situation--she is the one on the mortgage and as a result he walks away with his credit intact when the property is foreclosed on--even though he is on the deed. In this case the relationship had no baring (they are not married) on the situation.
You may want to start working on a short sale-see the link below.
Best Of Luck,
This is a good one. I'm with Scott. You do need to speak with an attorney. But a good educated guess is that you didn't guarantee the note; your partner did.
At any rate, you guys may want to consider a short sale. They are getting easier these day.
Jessie Cuddy, Realtor
Boston Bayside Properties
2253a Dorchester Avenue
Dorchester, MA 02124
Hope that helps,