My husband is not on the lease and has been out of the country for almost 2 years. Does he have a right to enter the house without my permission?

Short answer: "no."  His rights stem from whether he has a legal claim to the location, not his marital status to you.  If he is not on the lease, simply do not let him in.  If he has a key, you can change the locks (if permitted by your lease).  If the situation is that confrontational, however, you might be better served by a temporary protective order or an order for exclusive possession issued in a divorce action.  Either way, it is probably wise to consult a family law specialist.