Lawyers are free to fire their clients, just as their clients are free to fire them. If she feels that she is not going to win the case, she is going to advise some other course of action.
I understand this is hard WTBH, but look at it from the lawyer's perspective-she just might not be able to legally win the case. I don't think it's personal. She doesn't know how he really works, she doesn't know what he is capable of, and no matter who you get for a lawyer, that will always be an uphill battle-proving that he is a serious threat to the kids. The easiest and cheapest way out is to settle, and that is all she is trying to do.
That said, since I have to take the lawyer's side for a minute, I don't think you are wrong at all. I think if she is not willing to continue the fight, which you are paying her for, then find someone else who will continue the fight. DO NOT EVER do it on your own. It's too hard, too complicated, and you will lose. Ask her if she has any recommendations for someone else, continue to pay her a little bit at a time, and work out an arrangement with the new lawyer.
And the good news is, if you change lawyers, she has to hand over all of her files to you to give to the new lawyer. So, much of the work is already done.