Poor, poor you.
The first thing that I would say is that, unless your DH has comitted an act of gross misconduct or has a previous warning on his record, it would be difficult for his employer to dismiss him fairly at this stage (however ONLY if he has over a year of service). That is not to say however that they wont do that and risk that he bring an Employment Tribunal claim.
On the basis of what I have said, do you think it is likely that they will dismiss? If you think they will and that potentially it would be unfair, then I would check your home insurance and see if you have legal expenses cover. If you do, then this should cover a situation such as this and hopefully will be of assistance. It should also make both of you feel more in control as you will have a plan if DH is dismissed.
If DH has less than one year of service then his rights are much less unless he has some kind of discrimination or whistleblowing claim, which seems unlikely from what you have said.
Therefore, my advice would be that you discuss with DH the fact that you need to to talk about this with a trusted family member. It is too much of a burden for you to deal with on your own and you may need their financial/practical assistance as well as help on the emotional side.
If it looks like he is going to be dismissed, then I would also start speaking to the lender, other creditors etc to see if you can come to some arrangement regarding your debts etc if that is going to be an issue. Again, if you can bear to frontload this too then that should help the feelings of lack of control and fright a bit.
Once you have done all the fire-fighting and found out the result of the disciplinary hearing, then I would deal with the issue fo DH not discussing this with you and also whether he actually wants to work in the field he is working in at the moment. It sounds like he is self-sabotating or "acting out". It maybe that he has to keep working in that profession and, if that is the case, he needs to accept that and get on with it. However, these are issues for another day
I hope this helps a bit and that all works out. It could be that, if he puts a very good face on it at the disciplinary hearing, he is only given a final written warning and an other chance.