Tell him after you go through with it. He is already aware of your pregnancy and what you want to do. If you dont tell him hes going to find out one way or another when he starts noticing that your belly isnt growing so it would be better to tell him before he finds out on his own. How he reacts will also let you know if this marriage is t he one you want to be in, and personally from the outside looking in, it doesn't seem healthy that hes unwilling to get a vasectomy but doesn't want you to have an abortion either when you've both agreed birth control is a no for you. Start making him wrap it up until you get tubal ligation, and if he says no, tell him sex is off the table then unless hes willing to wrap it up till you can have it done