What am I supposed to do?

(Sorry for the rambling)
I made a post back in September of 2020 explaining about my grandmas memory. Recently, it seems as though she is spiraling once again and her memory is a bit foggy, she’s mixing up her words a bit more than she use to, and it’s the little things that she is saying that I am noticing something is off about her memory. I know that she is 76 (going on 77), but it’s getting to the point where I am scared that her memory decline is accelerating. I haven’t approached her youngest son (the trustworthy one) about this.

I also stated as to how my grandmother's children have no interest in giving me some help with taking her to her doctors appointments which are now increasing due to her kidney problems. They have also started belittling everything, they always tell my grandmother that I should be “doing more around the house”, when in fact one of her daughters only calls her one-two times a month & she has no idea what I do.

After taking some of you alls advice (on a previous post on here), I did get some much needed therapy help for a while and I was diagnosed with anxiety disorder (I did stop the therapy), but I am looking to resume this year. My problem now, is that I have started to feel the agitation of everything coming down on me again. My mental health has taken a steep decline and I feel more and more anger everyday from the lack of care of her children and it makes me want to runaway (even at the age of 24, going on 25) and let her children step up. However, I feel that I’m responsible for my grandma's well being and I’m afraid that they’ll neglect her. I am afraid that my resentment & anger is going to cause me to blow up and snap. All of this going on in my home life and then the pressure in my work life is getting to be too much and have driven me to thoughts of offing myself.

I really just want to drop everything and disappear from this family without a trace, but what am I to do?