I think it is not wise to get preggy without letting your husband knowing. Try to put yourself in his shoe. If you didnt want to have kid, he tried to use ways to make you pregnant and not letting you know, how would you feel? If it was an accident, then no choice.
Some guys have fear cos sometimes they are afraid. Trust me, they are even if they never show or even speaks. It is a lifetime commitment, taking up most time, money and sometimes other factors. Many things arise if "accident" happened cos all not being prepared- mentally, financially and physically.
Trying to conceive should be a joyful task. Welcoming a new born is always a bundle of joy.
Reconsider my personal advice. Good day!