Worstfear:
I am sorry for the suffering you are experiencing. Your wife made a choice and now you both will suffer. However, your suffering can end sooner by coming to terms with reality - happiness comes from inside of us and not from an external source. Do not put your happiness in her hands or the hands of anyone else. When you do you become that person's slave. She made her choice and her actions are hers alone to own. It is not your fault.
You are asking for advice on what to do. I recommend first and for most to take care of your health, both physically and mentally. Be sure to eat healthy, exercise, and get sleep. Find someone to talk to and seek the help of a therapist is if you feel the need.
Second, seek legal counsel to assist with the divorce. I would not seek revenge or be spiteful as that will only bring you down and cause regret down the road. Love is the sacrifice of the self for the other with no expectation of reciprocation. Romance is the wanting of someone else to satisfy your wants, cravings, and desires. Romance is the craving of joy or pleasure from someone else physically or in a way that builds the ego.
Adultery is the only Biblically approved reason for a divorce. It doesn't mean you have to get a divorce. She made the choice. Everything is on her.