harman, how come he is in the house? Have you spoken to a solicitor yet? Your living conditions sound impossible, even without all the emotional stuff, and you and the children should be in the house, not him.
If seeing a solicitor is too difficult or expensive or something could you go to the CAB and see what your legal position is? Surely it should be possible for you to get back in? (Or could you go back "with" him and then change the locks when he's out?)
If not, are there any housing associations where you are? I think they are a better source of housing these days. You are so overcrowded where you are surely you would be high priority?
You can probably tell from the number of question marks that I know sod-all about this but I wish I could help.
Please don't beat yourself up about the occasional cig! Hope you can find somewhere to live soon. Hugs.