So very sorry op, this is truly horrible for you, but you have no choice but to be strong for your daughter and son.
Keep telling your DD how much you love her and that in time she will feel better, can you get her some counselling?
As for money can you get a lodger to help with bills, if you have a spare room you can earn up to £7,500 tax free per year. Its easy money, also if you chose carefully, (a woman is safer) it can be fun.
Time to be very strong and take as much money from any joint accounts and put into just yours, you will need to secure your home and future.
Tell EXH he has to start paying you maintenance asap, really fight hard for this and as much as possible, it is the least he can do.
Get CPS advice.
Brush up Cv and get online to look for work, l know you must be reeling but you need to be job hunting, and also this will provide a good example to your DD.
Good Luck op, and l am so sorry..