I have a few questions:
Is either you or W considered his “primary” or are both of your relationships with him considered equal?
You knew that W was tolerating the idea of your relationship with him when you decided to move to a different state and move in with him?
Are you willing to be in a relationship with someone who hides information from his partners?
What are the future plans for these relationships (yours and your boyfriends, you boyfriends and Ws)? You live with your boyfriend now and he spend half of his nights with his other partner is that the plan in the future? Are any of you the marrying having kids types?
When he had sex with his ex did he use protection?
What are your safer sex agreements between the three of you?
What do you want this relationship to look like? Be honest would you rather he not be dating W? Would you rather be monogamous? Would you rather have 80% of his time? (knowing what you want and would like out of the relationship is important in moving forward)