If you really really want the baby and you are financially independant then tell your hu*****and the truth and ask for forgivness...If he accepts the baby then that is best thing ever happen to you...Otherwise you have to prepare to raise the child on your own...you may ask the brother to pay child support.
If you financially depending on your hu*****and then you are at his mercy...after all you made this mistake...There are consequences for what we have done in life.
BTW, Good thing is that you married a non-Chinese/non-Asian hu*****and so that you still have an option of remaining silience...:)