There is an unspoken "code" that spreads like leprosy among JWs, dear Miz Josie (the greatest of love and peace to you and your dear household!)... that goes something like "Thou shalt not ever apologize... to anyone... for anything." The GB continually sets that example, first and foremost, followed by DO/CO's, elders, and then on down the line. I think that's one of the reasons that some folks here look suspiciously on apologies - they're just not used to them or have never received genuine ones. Your dear mother appears to have succumbed to this "disease".
While I tend to agree with dear OUTLAW (the greatest of love and peace to you, as well, my friend!), I would tell you to never say never, if you can do that... because sometimes folks DO change, even at the last hour. That is the reason for hope, sometimes: regardless of how they treat US... we wish the best for THEM.
I do think you are quite wise for not falling for her games any longer, though - such only further enables and encourages people to continue in their bad behavior. I would not tolerate it, then, for the benefit of HER progress, as well as the well-being of MY family. That doesn't mean I would cut her off, though (which I know you're not saying). Rather, I would simply tell her, "See, Mom, can't do it 'cause here's what happens... and I'm just not going there with you anymore. I'm done, really. Life's too short and I've got a family to care for and so no time to play these games with you anymore. We're both grown and from this point on I intend to act like it... regardless of what YOU do." Or something like that.
But that's me, of course. You know your mama, girl... and sound like you might now know how to "handle" her. I will say, though, don't let her... or ANYONE... suck the "life" out of you. Hard to get it back once that happens.
Take care... and may JAH bless you and your household and grant you all peace... especially with this matter!
YOUR servant, sistah... and a slave of Christ,
SA