Wow, Jefe, I am so sorry to hear the additional things going on in your life. Take a deep breath and know that you are doing the best you can for Grandma, don't take a word she says personally. I watched my Grandmother decline mentally for 10 years and I know how it can get to you.
Please do something nice for yourself today, even a tiny little something to remind you that there are people all over the world who care about you.