Well you can avoid him nicely by saying "oh i'd love to but i'm sorry, i'm just not available" until your husband can go with you. This can be repeated the rest of your life if you want.
Or you can learn how to deflect him. Just because someone asks you questions, and probes, does not mean you have to answer. It's a built in response from school age that we have to answer when asked a question, but we don't. Answering questions with other questions "So when are you going to have kids?"="Oh how soon do you need to know?" or "have you been gaining weight?"="how kind of you to take an interest in my health. +change of subject".
Be ready for the digging probes, and just learn to bat them away, as you would a tennis ball flying at your head. Practice some vague deflections in your head, running questions he's asked you in the past through as a practice, and before you know it, he'll learn that he's not going to get any satisfaction out of interrogating you.
But remember, always ALWAYS do it politely. Manners can be used for evil satisfaction as much as being a goody-two-shoes, but it's way more fun to use them to keep others on their toes.