Help me please before I go insane...

"Hi Mark, I had emailed you earlier in the year about my 17 year old. I am writing again to seek your advice. I have read the email from the "Sad Mom" under the Empty Nest Syndrome tab linked to your email and I must say I am suffering almost the same fate now as her. My 17 year old daughter has now moved out of home to be with her father whom she hasn’t had much time for in recent times due to them not seeing eye to eye. Now that she has moved in with him it seems that he is giving in to her every demand. My daughter is now seeing an 18 year old who comes from a broken home, whose father was abusive. This guy jumps from house to house after being kicked out of his fathers house, he moves to his mothers, then he will get kicked out of there so he moves in with his brother who lives with his de facto and newborn child and that’s where he lives at the moment. He just so happens to live just around the corner from where my daughter’s father is living so it is very convenie...