Sorry you an the kids are going through this. I look at my 4 yr old Grandson an cry alot too. I'll never understand how a mother can walk out the door an never think of thier child. It sounds awful but at times I almost hate my AD because sshe doesn't love her son enough too stay off drugs an away from drug users.
As far as getting help from social services a lady I know has temperory guradianship of her granddaughter (mothers in jail) anyway she told the ******* Health people what was going on, an they said she could get money from social service if she needed it. Do the kids have insurance if not might want to check it out then maybe they could tell you how to get some help.
Again I have to say the kids are very lucky to have you watching out for them an loving them. You an your husband are wonderful people.