There are a few quick points I can make (disclaimer: I'm not a lawyer, but I do have a law degree.)
The debt against the family home is not valid if one spouse didn't actively consent - there is established case law on that issue. It's a legal no-brainer that banks and building societies should check out the existence and/or consent of any spouse before issuing a loan. (I seem to recall that that's the case whether or not the spouse is a named owner, because an assumed trust is deemed to exist on a family home.)
BUT - this doesn't apply to a house sale. If you are not registered as an owner of your property, you need to lodge a Class F Land Charge with the Land Registry. This warns anyone thinking of buying the house that they can't without your say-so. Without that info being held by the Land Registry your husband could sell the house without you being able to stop him, and then you'd be fighting over the profits, rather than residence.
You probably don't want to be stressing your salary prospects. In a divorce, the priority is the children, followed by the weaker party. You'd probably get to keep the house at least until the kids are adult, if it's 4 bed or smaller, and if you emphasise the need to be a SAHM until the kids are at secondary school you will possibly get a better settlement on that basis.
Good lawyers are vital. You don't necessarily get the best from the most expensive though - you need one who is committed to helping you. Mediation can be great but it can also involve lawyers who aren't tough enough when they need to be, which is the flipside of pointlessly aggressive. Still,
www.resolution.org.uk
- because the most expensive divorces mean lawyers bills can match assets. If you can do this with as little bloodshed as possible, the kids and your finances will obviously benefit.
Finally, I'm so incredibly sorry. This must be hell.