Okay...take a deep breath (or 3), count to 10 (or 100), go for a walk or a bike ride or whatever healthy thing you can do for your body, mind and spirit...you need to take a break from your situation to let your emotions cool down.
Go dark and use that time away not to think about her and obsess about the situation between her and om, but rather to keep focusing on how to make YOU better and spending quality time with the kids. You don't have to make any decisions right now regarding your marriage. Some time away may give you both a chance to miss the friendship you've built over the last few weeks. If all the things you say about om are true (and it sounds like your w suspects they may be true, as well), then he will show his true colors in time. You don't need to bring him up anymore...that only makes you appear jealous, enraged and controlling. Also, no more involving the in-laws in your marital troubles. Continue communicating (pleasantly, since you all are getting along better) about the kids, but leave it at that.
If you continue working on YOU, your true colors as a good person will show in time just as om's questionable character will. Take care, lc4