I cosigned a home for my sis and her exboyfriends and now her xboyfriend don't want to pay for the house. He put it on a short sale.And he had a second loan with my sis. What should I do?Is the lender will come to me and force to pay for the house? But I don't live therer. My name is not on the title.The thing is I am making good money. Should I nigotiate with the bank to buy the house??

A co-signer guarantees the loan if the primary signer defaults. So, yes, when the loan is in default, they will come after you.

If you want to buy the house, that's up to you, but you would then be solely responsible for the loan. So I'm not sure what advantage that gives you. You would be better off letting them do a short sale.