Another hard day; following through from a bad night!

It is now so evident to me why I had to make the decision I did in July of last year. Had another bad night with my 11 year old son last night. He has no respect for me or what I have to say and will take no discipline that I hand out. He has to answer back at every opportunity and shows me such little respect. I know this is partly down to learnt behaviour from seeing his father treat me with no respect for as long as he can remember. I guess the situation is having its effect to and the fact that he is a hormonal 11 year old just adds to the problem. I am not giving him mixed messages as far as discipline goes, what I say I stick to. His behaviour has an effect on all the family. My 5 year old was woken up by him last night and was still awake at near on midnight. My link worker from the Family Welfare Association was supposed to come and see me today, but she is off work ill. My 9 year old missed her therapy session last week for the same reason. I had to take my son to school this morning because he missed the bus trying to take issue with his punishment. I have since spoken to his form teacher (who is new and I now find out knew nothing of our situation) who says he has no trouble at school; they have no issue with respect and he works hard. I know things are probably going to get even worse once they find out that their father no longer wants to have any direct contact with them for the forseeable future. I still have not brought myself to tell the children (although in my defence I am still waiting clarification from his solicitor as to what he actually means by the present time). How do you broach the subject of daddy not wanting to see children of 1, 3, 5, 9 & 11 years of age? My son commented last night that he didn't care that he had made me cry. I have been so blinkered to think that he wasn't picking up on my relationship with his father and the way he treated me. How do I stop him turning out like his father and carrying it through to another generation? I really don't know what else to do! I don't want my children to turn out bad because of my life decisions; I done what I did more for them than myself but is it already too late to turn my 11 year old around? It is clear that the issue of no respect only relates to me and his siblings (exactly what he was exposed to during my marriage). I feel so much guilt for what I have put my children through; they didn't ask for any of this. I can't turn the clock back and he will always be their father, whether he chooses to see them or not. He continues to abuse us through not having direct contact with the children. Does he have mental health issues or is he just a bad man? I really don't know which one would be easier to deal with. If he was just bad then maybe I could hate him, but I don't believe he is bad; I truly believe he has deep routed issues from his childhood that make him prone to addiction and all that goes with it. I don't believe he ever had a good father-son relationship and even other family relationships appear to have been flawed. What do I tell the children? If my mum told me tomorrow that my dad no longer wanted to see me I would be devestated and I am 34 years old so how can I expect my young children to take in news like that? And I still have 3 court appointments looming in the very near future. I just don't know how I am going to get through the next few weeks. I know I will because I have to for the sake of my 5 lovely (yes and even my 11 yo) children. I just don't know what sort of a wreck of a person will emerge the other side. It is unlikely that the court appointments will be the last, oh no he is out to make life as difficult for me as possible. Well, I guess life goes on, how ever hard!