If the loan is secured aganst your property then you could lose it if payments aren't kept up. Is it a house in the UK or in Spain? In the UK, if there are joint property owners a loan company should check the names on the deeds. If it is joint names on the deeds, then both are needed to give authority before a loan can be lodged against the property. If it is an unsecured loan, then no, they can't take your house, but you must attend the county court to state your case. If you don't go to the court, the judge could then issue a charging order against your other halfs half of the property.
Reading your post again suggests he has an unsecured loan. I would say no to using a secured loan as he could walk off owing the loan company, they will then take your property if you can't keep up his payments. Whatever though, make sure you find out when the/ if a court hearing is to be held.
Mark