I can't contribute to heavily on the jealousy issue, other than to suggest that you try to define your jealous feelings in more precise terms that do not use the word "jealousy".
Usually there are underlying issues with jealousy that can be obfuscated by the more general term. Sometimes when someone picks apart what the jealousy means, they can get a better understanding of what their fears, envy or possessive instincts come from.
One other point I would raise would be that if it were me, I would take some time and address the breakdown in trust that occurred while your partner was having an affair on the sly. IMHO, there shouldn't be any justifiable reason for that type of dishonesty, and living in a poly relationship demands much more, not less, honesty and communication.