hm, bizarre circumstance. I feel for you.
I would suggest she look at the jealousy issue again. After all, the two of you were monogamous together for a long time and now she has chosen to share you. Perhaps she is not conscious of the fact that she needs to feel she is respected/appreciated for the time she has spent with you. I know I would struggle with that.... even though I have compersion and would enjoy the arrangement you have.
Perhaps she is not focusing on her life outside of your "v"? Maybe on the nights that you are with your other she needs to be more socially active.... maybe she needs to have her own "other" love?
Perhaps there is something rising out of her unconscious around you and your other partner as there seems to be a cycle of her being angry after you have spent the night with her? I would hate for that cycle to become entrenched. I really don't know your details, but hope that something comes out of starting this thread and there is some movement......
If I were her I would spend a good long time on my own, perhaps away from home, to meditate on it and focus on myself. I would also spend some time talking with your other when you are not there to see if she can shed some light on the issue. I know you love both of them very much, but sometimes we all need some ranting time.
I hope some of these questions are helpful....