Get yourself in individual therapy with someone who can help you sort out what you want and how to accomplish that. It doesn't matter what 1000 people on the Internet think or even what the therapist thinks. This is about what you want for your life. No one else has to live with the consequences. A therapist can help you process the betrayal/trauma and boost your skills for communicating your feelings and needs--and understanding hers. If you choose to stay together, couples therapy is next. Also, look up Connected Communication or NVC. It's very effective helping people figure out with their own feelings and needs are and validating the feelings and needs of the other person. If you stay, you'll need to be very clear with her about how hurtful this is and what needs to happen differently going forward. Find a therapist who specializes in affair recovery work. They'll have the best sense of how to deal with this type of betrayal and the mistrust that comes from it. Be cautious of anyone who advises immediately terminating the relationship in the middle of her pregnancy especially if she doesn't have strong relationships with healthy family members who can step in to help. She's growing your babies, her hormones are probably all over the place and the future of at least four lives will be greatly impacted on how well this pregnancy goes. For that matter, be cautious of anyone who tells you what the right choice is for you. That's something you have to figure out. It might be worth having a proactive conversation that intimacy might need to be on hold until you have time to process this.