Dear Prudence: During my six-year marriage, I have had a cordial relationship with my husband's mother. I am now pregnant with his family's first grandchild. My husband and I decided that we didn't want to know the sex before the birth. My mother-in-law was livid even though I tried to placate her by using the obstetrician she suggested and allowing her to attend some of my prenatal appointments.

My doctor's staff was aware of our decision not to know the baby's sex, but after one sonogram I was surprised to see my mother-in-law at the office smiling ear to ear. A few days later I had messages congratulating me on my baby girl! My mother-in-law wheedled the information out of the ultrasound technician, who is a friend of hers, then announced it. I threatened the clinic with legal action and found a new doctor mid-pregnancy.

My mother-in-law is smug about her tactics and told me that if I "still had a mother," I wouldn't be so selfish. (I was orphaned at age 14.) I can't express how betrayed and hurt I am by this. My husband sides with me and we've made a birthing plan that excludes her from the facility until we've been released. Am I being too vengeful here? How do I overcome this feeling of betrayal?

Prudence says: I guess you could consider yourself lucky your mother-in-law didn't pop out of the closet while you and your husband were trying to conceive, like one of those terrifying mothers in the Old Spice commercials. But how utterly unnerving to have found her lurking at your doctor appointment. After the technician violated your privacy, you were right to have found another practitioner. It should also be comforting that this obstetrician understands your mother-in-law needs to be treated as a security risk. Thank goodness your husband is standing firm with you. Too often, I hear about sons of such mothers who have been trained since childhood to give in, and who find it easier even in adulthood to avoid the drama and accede to their demands.

Your mother-in-law grew up in an era in which everyone had to wait for the baby to be born in order to find out its sex. So it's bizarre that she's obsessed with a piece of information that was to be revealed soon enough. But she has proven herself unable to distinguish between her desires and someone else's. Given her remark to you about your deceased mother, she is also cruel and insensitive.

Your husband should explain to his mother that because of her behavior during your pregnancy you two are on hiatus from her. Say that it would be sad not to have her in your child's life, but if she wants to enjoy being a grandmother, a basic requirement is that she treat her daughter-in-law with respect. An apology from her and a recognition that she needs to do better would be a start. But in the absence of that, after the baby is born and you feel ready, allow her some short visits to see if she seems capable of reform.

You're not being vengeful; she's the one who has to regain your trust. And don't let her terrible behavior make you engage in a stealth birth. You and your husband shouldn't feel that becoming parents is something to keep clandestine.

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