Keep detailed notes, and when you really can't stand it any longer consult with a local Family Law attorney. If she disparages you in front of the children, or withholds visitation, you may have grounds for a Petition. However, until it affects your relationship with the kids, you are better off trying to be thick skinned about it.
I am not your attorney and any posts/messages or responses to posts/messages can not establish an attorney-client relationship. www.PatchogueAttorney.com You should not rely upon free legal advice and I disclaim any liability for the results if you do.
Review your final decree, and if applicable, any subsequent modifications to your visitation and custody arrangement. Are there any provisions relating to no overnight adult guests or live-ins when the children are present? Telling you to cave is a mind game, but in itself won't get far with a court, so the advice of thick skin is very appropriate. Denial of visitation or ignoring other aspects of the custody and visitation terms is another matter. Just don't try to make a small molehill into the Catskills. Judges tend to really not like overstated claims.
Sign up to receive a 5-part series of useful information and advice about child custody law.