I completely understand how you feel. Since the D is final maybe you could try to do some things together again, without OW of course. This might seem like a crazy statement, but the four of you are still a family, but in a different way. How did you feel you were treated during the outing? That's going to be really important going forward. Think about whether spending time together will start a new friendship. I really believe you all can be close again even if you and xh are just supportive friends. Depending what you ultimately want that could go a long way toward starting a lasting relationship of some kind. It might be too soon. Only you know what you feel comfortable with.
You and your kids have probably become pretty close since bd and now the person who caused all the grief wants to share a part of the new life that you and the kids created. Afterward, he returns to his other life. I can understand why you see that as cake eating. It's also an opportunity for him to see and experience the new you.
I'll be curious about how the weekend goes. In the spirit of DBing, can you treat xh like a friend or neighbor? Please tell me he's not bringing OW.
