Their behaviour is beyond disgusting, they took away your right to a relationship with your own father and have the audacity to tell you to carry on with that, the fact they blame not being able to have their own kids is a joke and doesn’t excuse the absolutely atrocious thing they did, honestly I’d start a relationship with your bio dad and start cutting back the relationship with them, they had no right stopping visitation there’s no excuse for that even if they were worried, you should’ve been the priority not them
this is like the story rapunzel.
OP, first off I’m so very happy that you’ve finally met your Biological Father! That’s wonderful news and I’m so happy for you!!
Now to address your adoptive family. The bottom line is this. Nobody has the right to treat you like garbage and you’ve done nothing wrong here. Emotionally healthy parents would have encouraged you to seek your roots, as your identity is extremely important for emotional health. They should have allowed you and your father to choose if you wanted a relationship.
If you love your adopted family still, I’d suggest that you give them an ultimatum: they must go to counseling with you so that they can learn to stop being manipulative and emotionally abusive. Regardless of what they do, what you should do is to learn to set and maintain healthy boundaries and people who don’t respect them Have no place in your life. I wish you all the best in all your endeavors!