It's not marriage if one or both of your in-laws isn't an interfering busybody. Get her to apologize, or threaten to take away her 10am mimosas.

You need to have a nice, long talk with Mrs. Allen

Oh well, maybe that's her way of saying that she's chipping in for the ceremony.
Congratulations on getting married tho 🎊

You deserve it. If you want to keep a secret, the only people that should know about it are the people that need to know about it. In this case, you and your husband.

You realize that two witnesses are needed and the husbands mom could have easily been one of those right?

She may have been but she didn't need to be. There is nothing that actually dicatates that your two witnesses have to be people close to you. You can use literally any people as witnesses who are willing to sign as witnesses. So if the marriage was meant to be a secret, the OP would have been better off asking two random people who happened to be near the courthouse or whatever to act as witnesses.

Absolutely does not deserve for someone else to tell her secret... would be very hard to hide from your parents and you expect your parents to have your back. This is not your fault at all OP!!!! You can’t control what someone else does when you’ve asked them not to. Shame on her!

A witness is required for a courtroom marriage, and maybe they chose OP’s now mother in law.

Wow now ya know she can't keep a secret,time to have a sit-down talk and find out why she broke your trust,this is important to know where you stand in the family if the new hubby doesn't support you well time to go it'll only hey far worse in the future if you don't.

She did 3 things you specifically asked her not to do? See a pattern emerging?

Eventually, you’ll have her sit for your kids and you can tell her she’s forbidden to give them any broccoli.

Next thing you know, she'll be kidnapping the grandchildren while they are at their other grandmother's house and the police will find them all at Disneyland, eating ice cream in a Mickey Mouse hat.

This doesn't bode well for what sort of Monster-in-Law she's going to be in the future.

She was just giving you a taste of what having a mother-in-law is like!

That’s monster-in-laws for you!!

getting married and keeping it secret is just stupid.