Haven't posted to your thread before, but have been following your sitch. It was your son's decision to go live with his father, no? I am not familiar with the laws in the UK, but wouldn't your H need concrete proof of abuse for him to take her away from you if she wants to stay? You are a great parent, your H, NOT! Just the fact he wants to bring D13 into a house where he is living with his adultery partner will not be in his favor.
What bullsh*t has he accused you of? He hasn't swayed your son into supporting him in this, has he? It seems to me that he's made a HUGE tactical error by refusing to help with your eldest D's college tuition (but he pays for OW's, right?). She won't have good things to say about him if questioned.
