Annulment For Adoption

I (mid 20s) recently agreed to be adopted by my step parent. There was an agreement made (that I was for lacked of better words forced to accept and go along with) that if, met my sibling and I agreed to get adopted. Since the adoption they wasted no time before getting into their antics and behaviors again. Recently they have stated that they have "bought and paid for us" and "I'm going to be making your medical decision your partner (7+years together) isn't a part of MY family and if anything happens to you I get your life insurance because I bought and paid for you"(my health is in good standing there's nothing wrong with me but I have a risky job)

Any ideas on how to get the adoption reversed without the other party being able to interfere?