Hi Boobars ,
Please don't stress about this as the courts will not take the children from you,unless there is something else that makes you think they would,why would he think he would be entitled to half your money this strikes me as very odd ,for a start your partners money is none of his business ,i am guessing he doesn't pay child support but if he thought he could get the children he is expecting you to pay him??,does he want the children so he can get a house? anyway just don't worry about anything till you get a letter saying he's taking you to court ,he already see's the children so in my opinion it won't come to that
Good luck Cherry x