orange sometimes they do, sometimes they don't.... I do think that when they act so rashly, that they really aren't thinking about what they are doing.
I too want my XH to suffer one day, to deeply regret it. He probably will because she is already divorced twice at the age of 33, having both times cheated on her husband. My Xh is 50, and totally besotted with her. I hope that he stays that way until she cheats on him too, so that his heart is totally broken and he knows how it feels.... yes I am 3 years on, but I will always despise him for walking out on me and DD.
Hopefully karma will bite him on the arse one day, but by then, you won't care any more.
The main thing for you is to sort your finances out. Go to the DWP, get the Income Support, sort out the rent/council tax benefit, ring the council tax anyway to get the 25% discount applied while your benefits are being sorted out. Get into the system as quick as you can. You should also then qualify for free prescriptions etc.
Then once you have sorted all of that out, you can start looking for suitable work, whilst knowing that you have some money coming in.
I have just done a quick calc on the tax credits calculator and assuming that you have income support and 3 DC, it says that you are entitled to £675 from today to 5 April, so that is just one month.... if you can get your new claim sorted today, you can advise them as and when any changes are made.