Well, if you’re on title, there’s no way he can legally refinance without your written consent at closing. Guess the question to examine would be exactly how much the new loan size will be compared with the existing. Obviously the amount you owe in 2018 will impact your proceeds from the sale of the home, and potentially even the ability to sell it if equity is low. I’d sure want to have my attorney examine all the loan docs PRIOR to closing. That’s really the best route to go…..