New to poly?

So I’ve just started having a sexual relationship with my best friend of 15 years! I’ve been secretly in love with her for most of the time. My husband of 22years knows. He is willing to let me be with her as long as he is a part of it. So he isn’t feeling like he is being cheated on. My husband and I communicate everything. I want her as a wife. My friend isn’t sure what she wants yet as this is all new to her. How does polyamory work? Is there jealousy? Do we have to keep our love life a secret? How does this work?