Thanks for the advice. Talk with the IC today and she says that there should be no problem with me revealing the identity of OM. Especially if there is a chance of W trying to bring him around OM one day acting like them getting together was just some random thing. But I will seriously take your advice on not bashing him to his mother. Even though her actions clearly show that she doesn't give a crap about either of us over OM.
S13 only met this guy once as the A was starting and W was parading us around his family as if we were all going to be the best of friends. Unless I showed S13 a picture of this guy and his family on FB, he likely wouldn't remember who this guy was. Especially since he lives in another state.