I live with My Grandmother and She yells and swears all the time at Me when I mess up. Can someone help Me?

She is Bipolar, and has a Colon disorder thing, and I feel bad because She can't eat like She used to. I have a problem with Wheat, but She let's Me eat Wheat a lot anyway sometimes. I have ADD, And I am on two Medications. Ritalin, and Zoloft. I hate taking pills because I am scared I'm going to choke on one. My Grandmother gets mad when I hide My pills instead of taking them, and She yells at Me, and She curses and calles Me bad words. I don't want to yell at Her, and I know I never should. She does voices of My dolls, and does YouTube videos with Me. She likes gore stuff, and She now thinks SiFi is stupid because it's not scary much anymore. (I agree! No offence to SiFi lovers.) I get upset when She yells, and I threaten Her. She dosn't have feelings, exept Anger. Iv'e never seen Her cry. Two years ago, Her and My Grandfather had a divorse. And it just now ended. I miss Him, but He didn't really love Me. And My Grandmother spends so much money keeping up the bills and stuff. Plus, she sacrafices what little money She has buying Me online game money, and buying Me the things I want. Like Pokemon plush and things like that. Also, My Wheat Free food costs a lot. I get really worried when She beats Me. I am 10, and I'm about to be 11. (My birthday is in August 9, a little while away! Thanks to everyone that says happy birthday to Me.) And yet She still spanks My hands and spanks Me. I tell Her I'm too old for that now, but She still treats Me like a Five-Year-Old. I don't like it when that happens. I want us to be happy together, and yet, I worry that She will send Me somewhere bad or try to kill Me. She has punished Me for the smallest little things, like spilling juice. I think She has stress, but it's not fair for Her to have Her Anger taken out on Me. Everyone does things wrong sometimes, but I want respect, even though I treat Her wrong sometimes. I don't want to be treated like I'm five. I am also in the 7th Grade, and I'm homeschooled. I worry that sometimes She dosn't love Me. So could someone please tell Me what I should do?