Loveless marriage but 3 beautiful children to consider?

In brief this is me - put in orphanage aged 2 and adopted by strict catholic parents aged 4. DREAM - to one day get married and have children of my own. Simple. My adoptive parents - relationship not so good - shame, but it's not easy I suppose, bringing up someone else's kid. Anyway, growing up developed flushing/roscea disorder - inherited! Not much fun, everyone thinks that your embarrassed easily, when it just comes on from many things! Affects the confidence alot and makes it difficult to find person to love me (and DREAM!). Finally find a man who accepts my red face and we marry - after 8yrs of dating - married now for 11yrs. DREAM finally fulfilled - 3 beautiful children all under 8yrs at present. One with mild autism. Problem - not children - although alot of work - no family support - but husband has switched off. Barely talks to me, can't be bothered to do anything properly and gives me the following answers - "It didn't occur to me", "I didn't think", "I'll do it next time" but he just doesn't care. I constantly work hard to help my children especially the one with special needs but my husband has never picked up a book or researched anything that might show he has an interest in helping his kids. When the children fall over, he ignores them and if I say "look! he just fell over," he says "I didn't see" even if they are crying. When he is meant to be supervising them, if something happens, he blames them - even the 3yr old. I tell him that when your in charge of a small child, you have to take the responsibility for them, especially when so young, but he doesn't see it. Treats them as if they are adults and they should have known! I try to talk about how everything has fallen apart and he just says O.K. O.K. Needless to say, we don't have sex anymore - I cannot risk becoming pregnant again with this man and I don't want sex with someone who is treating us like this. I am just about keeping us afloat at the moment. Our finances are not great and when I try to talk about it and express my anxieties about our situation and what we should do, he says "I'll look into it" - but he never does. I'm really frightened about our future. I often think that we should split as its awful being tied to someone who has decided to opt out, when there is so much responsibility. My big, big concern is our 3 children. They would be devastated and I do not want to jeopardise the progress of our special needs child, or the other two boys who do not see the flaws in their father yet as they are so young. I have no family and I lack confidence in myself. I'm pretty exhausted. I hope I don't sound sorry for myself, because I'm not, and although I may feel terrible about it all, I am not "depressed" - don't have time for it. I always wanted a real family, and now I have one, finally after all this time, but I'm fighting hard to keep it. Why is he doing this? It nearly feels like he's doing it on purpose. But why? If he wants to go, then maybe he should. I have a gut feeling that he wants to go (as the going has got tough) but his biggest fear is what people will think of him leaving us, instead of what it will do to us. The flaws didn't show too much before we had children, as he's fine at going on holidays and watching t.v. He has never stood by me when there has been incidents where a husband/friend would stick up for you but I didn't mind when it was just me, because I was grateful to have a boyfriend/husband. But now, he doesn't stick up for the children either and that's hard to stomach especially since my oldest has suffered bullying. I suppose its a feeling of being on my own with it all and this person just floats in the house and out and is called husband and daddy! What should I do? I was thinking that maybe I should do the stay together for the sake of the children scenario - until they grow up - and then we can call it a day. But that's harder than it seems with him, because he's opted out so much. Any serious advice please, this is our lives and although I do enjoy humour - this one isn't funny. Thank you and all the best to you all.