Refuse his calls (or calls where you know he will be in the background trying to communicate with you). Cease all communication. As long as he thinks there's a chance, he'll keep bothering you. As a method of last resort, you could tell him very clearly that if he keeps contacting you that you will have no choice but to then tell his wife. Obviously he's not serious about being married, his baby son, or much of anything at all. He has very little care for anyone that should be important to him. Stay away from this guy!