I don't know what the OP's diagnoses are, but I do know two things:
1) The foster care system is already busting at the seams. If you're seeing a psychiatrist and your mental health is stable, there's little if any reason why child protective services would be interested even in a preliminary interview. Even if some overzealous social worker did decide your diagnoses warranted further investigation, the word of your mental health provider carries significant weight in whether or not a case is even opened.
2) If your fear is preventing you from getting the level of mental healthcare you need, then you may be sabotaging yourself and creating the very situation that scares you - and your mental health provider won't be able to say that you took steps to remain stable. You haven't been honest with her since you first heard this story.
Another thing you might want to consider is that stories like this make the news for their relative rarity. Most family service workers don't want to take a kid from a decent home headed by a stable mentally ill parent only to put that kid into a crowded system among children who have been abused and will pass on their maladaptive behaviour.
Yes, there are bad social workers out there. In general, however, social workers are not your enemies; they're gateways to service provision.
You should be honest about your fears, so that your service provider can give you a realistic (rather than a skewed) take on how the system works; she could - and, unless there's something wrong with you that could pose a danger to yourself or others - she could probably put your fears to rest.
If, on the other hand, you actually do currently pose a danger to yourself or others, you owe it to your kids, and to yourself, to get help - even if that means temporarily turning the kids over to a trusted family member or friend. Once you're healthy and stable, then you can be a mother to your children. Until then, you're not doing anyone involved any favours.
If you ever read this, please talk about this with a mental health professional. Please. So many tragedies could have been avoided if the people involved took that leap of faith - and yes, I acknowledge it would be scary as hell to do - and done what was needed to take care of themselves so they would then be fit to care for their kids.
