How can my boyfriend legally adopting my son?

He cannot adopt your son unless you are married.

No. If you are married, both parties must petition the court for the adoption. Once you are divorced, you can file a petition for adoption solely...

Each court has its own local rules. Depending on the court in which you file your action for divorce, you may have to disclose that you are...

How do I file for divorce?

You would need to file a Petition for Divorce and have her served with it. Since you have been living separate and apart for the requisite time...