I got involved into polyamory relationship a year ago, completely unintentionally. It is four people, sleeping criss-cross, straight. We have intense jealousy issues.
Advice?
I'd start with those, then, have a look around on our site (a search or better still a tag search for "jealousy" could get you where you need to go), and post any particular thoughts, questions, or concerns that you may have.
Hope your situation works out. Polyamory's a challenging way to do relationships; not for everybody. You have to find out if it's right for you.