Welcome, ClariceK. *hug*
Setp #1 is talking to people that can help you get perspective, so you've gotten started.
Two things popped out to me on an emotional level in reading your story. First, you referred to your "Family." I don't know if that was intentional or not, but you used capital F and you called your situation a family--not help us or help me. This leads me to believe that on some level you identify your unit as important and as a (albeit non-traditional) family.
Second, you have a world of pain--sexual, physical, and emotional. There are many posts in these forums about jealousy. Tags will help you find those posts. As for the sexual abuse, I'm sure many here can offer words of advice. I have shared relationships with several women who had abuse in their backgrounds. They are each and every one precious and wonderful souls. It was very hard in most cases for them to feel a connection to a man, but I feel blessed that they would share some of themselves with me. You are precious, too. Your husband's actions speak volumes about his devotion to you, and I suspect it's because he has had the chance to see the inner you.
I suspect that your particular case of jealousy is complicated by feelings of frustration. I suspect that you worry about the disparity between your desire and your husbands. This is followed by opposing emotions of abandonment when he is with someone else and failure that you're not the providing that outlet. These are heavy things, and I'm not surprised that they have been hard on all involved. You might consider in-person counseling as that level of interaction may prove more effective for your acute situation.
In the meantime, there's a lot of information here, and a lot of people devoted to helping polys live happier, healthier lives.