KT, I wish I could just give you a big hug.
Things are looking positive for me finally right now and yet things have gone downhill for you again. I don't know what to say for you. I just wanted to lend you my support. J has kept within our agreements and I am greatful for that. She and husband are having their night tonight actually and Husband and I had a very long and intimate conversation last night to conquer some unresolved issues.
I think you might be holding back from your husband too much. Yes you want him to be happy and yes you don't want to hurt him or bring him discomfort but you also cannot take the full burden on yourself. I know that is what I did last week. I didn't want to weigh him down with my worries and hurt feelings and hardships which resulted in a very bad weekend of mood swings and fighting. We are talking much better this week because he is understanding what I am saying more and I am not holding back either. I have found a calm spot and we are communicating much better the last couple of days.
So I can only suggest that you step away for a day, go for a walk in the woods, take in nature and clear your head and then come back and talk talk talk with your husband. Talking to her obviously doesn't do any good. She is a manipulator and from the sounds of it doesn't want a polyamorous relationship. She wants to be a homewrecker. Big difference. So you and your husband need to get everything out between you so there are no misunderstandings and you can lean on each other.
I hope you are feeling better and PM any time you need to talk.