I read your post and the thing that stands out to me is the fact that your ex's wife is the one whom he had affair with while you were married to him.
People who have affairs with married men, live with the thrill of the chase and the excitement of getting away with something. Ironic thing about these type of people is that they really don't want the married man...and often when the man leaves his wife for this other woman, she suddenly has no interest in him...the fun and excitement is no longer there...and they will simply move onto, and yes you guessed it, to another married man.
As you posted, your ex's wife is continuing to have affairs...because of the excitement and not being able to live in a normal relationship without all these twists and turns. She is a very unhappy woman and needs this excitement.
So why is she stalking and harassing you...because of the thrill...obviously she has no life of her own unless she is causing havic and destroying someone else with an affair. Some women have affairs with married men and the wife/ex never knows they exist...and others get a thrill out of flashing the affair and hurting/destroying the wife as much as possible...they are thrill seekers who live and breed on other's pains.
My ex had several affairs on me, that I never knew of...then when he had his last affair, the woman caused me as much grief as imagineable...was out for total destruction (like your ex's wife)...she was bound and determined that she was out to prove something. In the end, when I finally escaped, she moved in with my ex...and before you knew it their relationship was over (I wasn't anywhere in the picture), because it had been based on her hatred of me and her determination to get my ex from me. It was all a game to her...and once she got what she thought she wanted, she got rid of him...she wasn't after him, but after the thrill.
In regards to your ex's wife slamming you in front of everyone, including your child, this just shows how insecure she is and also the fact that she has not released the fight is over...this is what her relationship and draw to your ex husband was...and as long as it is going, so is her relationship with your ex.
Think about it...what has this woman done with her life...she has no life...her life is about slamming you....her relationship is about slamming you...if she stops, she (in her mind) has nothing. She has to have a crisis happening every second of the day to survive because her life is so sucky.
How to handle...this is a tough one because you have a child who is thrown in the middle of her crazy world...and you of course want to protect your child. Since your child is 14 and in the court's eyes, she does have a voice, I would suggest that you contact an attorney about visitation issues. At this age, the judge will talk with the child, privately in his/her chambers, and get to the bottom of this craziness this child has been thrust into. Perhaps then, your ex will get a clue.
Until a judge hits your ex over the head, he is going to take his wife's side of everything...remember, he took her side and left you and your daughter for this woman...so his reasoning is obviously through his wife...always.
Hope this helps...good luck and keep us posted. In the meantime, feel free to vent away...sounds like you need a shoulder to collapse on after these years of torment.
An informed victim is an empowered victim enroute to recovery.