Aww hon, that is a very hard and sad story. I think that you should go to the doctor, your medical records are confidential and getting help shows awareness and good parenting in my eyes, as by helping yourself get better you help your family be happier.
As for the other issue, with cyfs, I think that if you take one of those plunket run parenting courses and then demonstrate using timeout or a 'naughty spot' for inappropriate behaviour (bad language (that doesn't mean I think your kids swear I was thinking more like saying 'bum, bum, bum') and hitting) then cyfs would be happy with that. I know that you shouldn't have to do that but for the sake of keeping your kids...