She can block his number, I believe, so he can neither text or call her. She can filter his emails to be deleted. She can tell him that if he continues to contact her she will get a court order. You can check on the laws to see what you need to do to sue him if he continues to interfere in your marriage.
There is NO reason for either of your to accommodate OMs needs. Time for you to stop. If W continues, I'd not begin reconciling, if I were you.
If this is really about accommodating your needs or Ws needs, the story may be different. But, I don't think it is helping your W to not establish firm boundaries with respect to the conditions you will live with -- those boundaries are about you, not about controlling OM or her.
