Cowscock? Just when you think everything is settling down, life comes and bites you in the ass doesn't it? 
Apologies if this is a bit long , your posts today really made me think.
Firstly though, how's the job going, have you started yet?
About your ex's suicide threats...agree with TheSilveryPussyCat that informing the police of the threats is good idea:
a) Them checking up on him might scare him straight
b) There was thread over Xmas where it was mentioned that new legislation came into force in early January about emotional abuse and coercive control. So going to the police will ensure his behaviour is on record. I don't know the ins and outs, Women's Aid will.
The other thing that really jumped out at me from your posts today was your deep compassion for your DSD.
a) You understand this is a difficult and scary time for her
b) You feel a lot of sympathy for her over how her dad treats her
c) But with the stealing and rudeness you know her behaviour is straying into dangerous territory- dangerous for you, dangerous for her, dangerous for the family unit
(By the way, do you think your ex is manipulating her to get at you now you are more immune to him? If so, that is a despicable way to treat a child, so damaging).
So I sense you are looking for a solution that reasserts some proper boundaries and behaviour, one that keeps both you and her safe. So that's how the devil's choice comes in
a) Find some way of making her dad look after her. Then he's not manipulating her into damaging you. But you think that's not a good option for her if at all avoidable as he is an arse who treats her badly already
or
b)look after her yourself as you are a better parent to her than either of her own but that could be dangerous for you and also will make her very conflicted and that can come out in all manner of troubles (stealing, rudeness, eating disorders- the no egg or beans thing could be her trying to assert some control on her life because she feels she has none. She could even be projecting how she feels about choosing you or her dad onto the eggs and beans situation- she doesn't want to choose but I could be reading too much into it).
So nobody can choose between the devil and the deep blue sea, so I've been racking my brains a bit. 
First two things are obviously police and Womens Aid as above.
Then I wondered if SS could help you by placing your DSd as a foster daughter, so there are formal boundaries, support and financial help. But i don't know if that is possible, perhaps other people will know more.
Then I wondered is CSA/CMS can offer any help and advice on this as you go through the process of making a claim for maintenance for DSD and DS.
Then I remembered Gingerbread the organisation that supports single parents. They gave my mum a lot of good advice when I was little. I also had a colleague who had worked for them for years and years, and she had a lot of good things to say about them. They have a helpline, local groups, a forum etc. They will know a lot of the legal in and outs and have experience of dealing with complex situations like this, from legal, practical and personal angles. I suspect they will be easier to deal with and bit more joined up than government agencies, who can be a bit too focused on their own area and nothing else IME.
Obviously as well, if your ex has to house DSD, that will force both his and the council's hand re accomodation. Although my impression is that you don't want that or think that is te best thing. You just want her to behave within safe boundaries. You understand this is horrible for her, but you also know it is no excuse for some of the things she is doing.
So, there is (comparatively speaking) a lot of emotional and mental health support available for under 18s, both via formal routes like schools/doctors and via charities. Maybe some counselling could help her to behave better (by reducing her fear/conflict/confusion and giving her a safe outlet).
I think Gingerbread would know about this. I was also able to find a list of organisations offering counselling in my area by googling "organisations offering counselling in " and a lot of those listed mentioned that they had specific services for u18s. So there may be a similar list for your area.
Wish I had a simple solution to offer you to all this. You've done so much already. But it's complicated isn't it?
&
or
? I do know a couple of simple things though
- You've done so much already you have every right to be really, really proud of yourself.
- How you've handled everything already shows that you will find a good & safe path through this, one step at a time.
Take care Cowscock