Limbo, your sitch is fairly new, so it is understandable that you are having these intense feelings.
Your H doesn’t know what he is doing right now. I don’t think he is happy. It must be very confusing to him as well. One day he feels that he needs to go to JW, and another day he wants your support when he is sick.
Think about it this way. Your H spending time with JW is bringing him closer to the reality. More time he spends with her, more things will come out. It cannot all be all shiny all the time for them. You need to be the safe harbor for him when the things start going sour with JW, and they will. You need to stay calm and positive, and no drama. Just pretend that you had an awakening and now is completely happy with your life.
Where is your son? Does he live with you, or he comes to visit? I know that your daughter is angry with her Dad, but what about your son?
M:50 H:52 S28 (my S from previous marriage) M:17 + 3 BD: 06/12 S: 06/12 - H works in another state