Unfortunately I think that the answer here may be yes: without a Court order terminating his rights tot he property in some way he has a right to re-enter the premises and you can not do anything to interfere with those rights like changing the locks, etc.  You do have a claim over and above the matter as to reimbursement of the money you have expended on the care maintenance and upkeep of the property over the time that he has been gone.  Hopefully he was on the mortgage as well to make it easier for you to prove that he had the obligation although it is not impossible otherwise.  I would check with an attorney in your area as to what you can do here.  Maybe it is time that you face him and bring up the subject of splitting the house.  You have the leverage of 2 years of payments.  Good luck.