I think my mom is losing it...

[Anonymous]

Ugh, my MIL is like that. She "feels stupid" and complains about it when we don't inform her. But when we do share information then she acts stupid, telling all extended family things that we asked her to keep private, doing the opposite of what we asked and she agreed to do, etc. This is why she will stay uninformed. I'd rather her deal with "feeling stupid" than face things that can't be undone.

[Anonymous]

My goodness, OP stop apologizing to this woman!
She does this because you let her.

As soon as you get the first text and see that she's off in a huff, you do not respond.
Time and silence are the best weapons. You call or text a week later (or whatever your rhythm is) with other news, and if she's still mad, then you hang up or stop texting under some pretext or other.
Don't engage, don't explain, don't get defensive or upset. Just ignore her when she behaves this way.