i would let him go. it's his son and it would make him feel a part of his life. let him see what he's missing. it may also upset the OW and make her react badly. that would be a good thing. be the better choice.
M:63 H:53 S:41, SS:28, SS:25, SD:23 M:15 T:16
Bomb:12/17/11, "I think we should go our separate ways." H moves to his mother's house, 4/1/12 12/21/12: H moves back home, piecing