Use the Jam
Like to pieces of toast rubbing together, things are coarse and rough and uncomfortable. You may try using an intermediary. AKA your husband. While you may feel hurt about his continued relationship with her, I would think that you would be aware that the nature of his love for her is sustaining for him in a manner separate from the love you share with him. If this woman still trusts your husband, I would suggest that you lean on him to help get across the depth of your sincerity. If she is all to blinded by her worries or false fears over you, your husband and the love he is sharing with her may be the key to getting her to come around. Love is an emotion, and thus a woefully illogical drive in us at times. But that is my two cents on the matter. Talk things over with your husband and see if he is willing to put in the good word for you.. to Validate your sincerity to this woman. If she manages to be willing to listen even a bit. That may help in her coming around to reconsider what possible biases she may have sent in her mind about you. I wish you well in your loves. And I pray that all things will turn out for the good in the end.