I say screw what people think about you!
Tell them. Most everyone will be excited for you and if they aren't then you don't need them in your life. You may have a few people that may question if that was the reason why you got married but you can simply tell them, "not at all, we were getting married whether we were pregnant or not". Or you can just tell them it's non of their business to question it! lol
but that's just me.. But I think people that really love and care for you will be supportive. As for FB you can always make it like a cutesy wedding thing where your hubby gave you a present a little early or say just to add to the excitement of just getting married we're having a baby!
But make sure DH is ok with announcing it, I'm sure if you just explain how excited you are he will understand. But CONGRATS on your baby boy!!! How many weeks are you?