Good job Marie751 for sending out that letter to your interfering sis-in-laws. Kudos to your husband and your sil #5 for apologizing. It's great that you'd started speaking your mind.
Parenthood is not a one-year contract to "try out" and quit when it's not working. I have met many parents who understood my husband's and my decision not to have children. They don't regret their own choice for having children, but they will not hesitate to confess they had a hard time bringing up children - emotionally, physically and financially. They certainly look forward to having grandchildren later in life but right now, they are looking forward to seeing their kids grown and start a life of their own. They acknowledged parenthood is a lifelong commitment and is not for everyone. This is speaking from their personal experience and from their heart, not a cliche.
My advice to respond to future "childless" question is to be calm. I have done it all my marriage when strangers, co-workers or anyone asked. I don't have anyone "imposing" their opinions on me. So it must have worked.
My rule is "Don't get upset or personal with your retort". It'll reinforce what they want to see -- that they hit a raw nerve in you, perhaps you're "secretly" wishing you're a mum but cannot. And it'll spur them to push up another notch asking more personal questions, like, you'll be happier with children if you're a good person. That's when you tell them affirmatively that both of you are happy with not having children. Don't engage in the drama, just be concise and comfortable with your choice.
About comments about you being selfish. I believe many of them said that because they don't know life any better. They never had a life of independence, hence, their neediness. Likely they don't believe they can have a great married life on their own -- without children.
Our family/ friends who understood our "childless" position would never make such careless remark as they know we are clear and happy with our choice. So they have no reason to ask us to trade our happiness for a role both of us are reluctant to take on. For what? To be like everyone else? And be unhappy on top of that! No, we won't settle.
You sound like you have a great married life - as can be seen from your husband's constant loving support. So play up the fact that you and your husband are happily living your dreams. Both of you don't see the need of adding children to your happy marriage now and also in the future. Don't be afraid to let them see you're happy with your own choice.
Enjoy your happy marriage and stay true to your heart.
