Well, don't wait for her to ask. Don't let the OM's presence intimidate you. Next time around, just let her know that you WANT to come along.
Women love assertive men.
Besides, she's still yours. Who knows, your presence may even dissuade him from making any further advances on your wife. That's why I'm telling you to get involved before it's too late. Don't let the OM's presence intimidate you. Next time around, just let her know that you WANT to come along.