Everyone is right. Let go of your H and focus on K. She is going to need you as I would be surprised if your H stepped up to the plate and mangaged both kids.
Are you still getting any CS from your H? If not, I would get the paperwork going again for that. All business!!!
Me: 46 FWS: 36 Married and Divorced 4/07, Pregnant 7/07,False R 7/07 Baby Girl born 3/08 Kicked him out because OW: 7/08 5/10 He realized what he had and lost. Moved home! REMARRIED 3/14/11!!