Soooo familiar.
You should know and understand: your mother's behaviour is not yours. What she does reflects on *her* not you. You are not her mother, she is not your willful disobedient child. She's your mother. She's an adult in her own right.If she chooses to act badly in public, that's not your problem to fix, that's on her.
If her texts are truly upsetting you and you can't stop reading them, and she will not stop sending them, you may have to block her number. My first goto would be to delete them after a cursory skim. Don't read, look for key words instead like "sick" or "hospital" or similar. If there aren't any important key words in the text, delete them. Again, if that's not possible, block her number.
I had to remove my mother from my FB (I never honestly should have added her, but we live in the same city and I'm still waiting for her to explode over that-I'm not sure she's realized it yet) and it's been much better. She's a very..religious conservative and I am very liberal egalitarian. She still hasn't realized that the reason her food is so bad at one of the pubs we occasionally meet at is because she talked about how anyone on minimum wage was a lazy bum who didn't deserve better in a nigh shout (most waitresses don't make much more than that).
I still have to apologize for her, but it doesn't bother me as much as it used to. You (unfortunately) get used to it-and when you realize it's her making herself look bad-it's a lot easier to do.
I still screen my calls-she can be pretty damned vicious and we've talked about boundaries and she's never respected them.
She's on good behaviour now, but I think she's had a talking to-either her Pastor told her to mind herself when she was expecting sympathy or my father gave her another ultimatum about her behaviour driving me and my sibling away...... or she wants something. I have no idea. I'll take what I can get while I can get it. At the moment, it's been almost a month and I'm waiting for it to explode (as it inevitably does).
In short: I totally get what you're going through. You're taking teh right steps to minimize the harm she can do, though if you can't get her to behave better via text, you should block her number, and you need to realize her actions reflect on *her* not you. *YOU* have nothing to be ashamed of or feel guilty over, She's a grown adult, if she can't behave that's her responsibility and reputation, not yours.
She may be the one who gestated you, but by now, you've probably paid that back in full with taxes and interest. You don't owe her, and if she wants to act like a spoiled child, then she can reap the benefits thereof.