Sorry to be that person, but are you sure it wasn't him that was guilty of a serious crime? He could have been in care for that reason.
I was wondering that as well. I wondered if maybe something had happened in the past, that involved him being the perpetrator, and that he why he is acting like he is.
Saying he will kill himself so that the school will feel sorry for your son and let him in, means he is either seriously unwell, or a massive attention-seeking drama queen.
Re, what @PovertyJetSet said on page 12, no he doesn't sound like a bad man, and most people are not saying that, but something is seriously amiss.
I get that he may have had a bad childhood, and may have 'issues' now relating to that, but none of it excuses forgetting/not being bothered to send off your son's application.
I am with @RubyRed from the previous page. Particularly the first paragraph.
Whatever the root of your DH's problems are, the point is that you have been the one who has acted to sort this out while he has created a drama that is all about him. Threatening suicide, I mean come on. Booking an appointment with the Head - well if anything comes of it then I will be glad to be wrong.
I was in a relationship with someone who repeatedly let me down like your DH. I tried so hard to soldier on for the sake of the kids to keep the family together. I just couldn't do it in the end. It takes two people to make a marriage work. It nearly broke me, I had a mental health crisis and became borderline alcoholic. .When I split up with him, he moved on to another partner within weeks because he really didn't love me at all, I was just a domestic functionary.
Society tells us we have to try and keep the family together for the sake of the children. But mothers deserve a life too, and not to be driven to near madness. Please put yourself first because no one else is going to.
Upshot is, although I know people have bad shit from the past, there comes a time where you can't keep using it as a crutch, or an excuse to treat people like shit, keep fucking up, and expecting someone else to pick up the pieces because of what happened to you. What if you didn't have them, you would have to sort shit yourself and make sure things didn't fuck up then!