I'm sorry for your experience. Therapy in this situation would be important in order to heal and rebuild yourself. But the jealousy/ insecurity is unrelated to what happened to you.

Your anger over him having fulfilling experiences is not a reason to make him dump his other partners. It is a reason for you to seek more therapy. Even if you feel that this has been unfair, and it has, he is innocent, and it would be selfish to deprive him of fulfilling experiences with his other partners because you are jealous, angry and frustrated with your own fortune.

It will eventually be important for you to figure out your longer term wants and needs. Would you want to continue with poly when you recover your energy and sexual confidence? Would you prefer mono? Will you be compatible in a longer term perspective?