I'm 10 years younger than my husband and now mother-in-law has moved in with Alzheimer's. I cant cope, any advice?

I need help dealing, feeling guilty because I do not want to do this my husband feels I am just being unreasonable, My stomach is in knots I cannot hardly even eat. my mother in law is in the kitchen every single time I go in there trying to help fix meals I let her help but I want to scream, no privacy, no time for me day or night now I put my grand daughter on the bus and now mother in law is here asking me how to do something all day because she don't remember how to do it or don't know because she is in our home now. I also have a seventeen yr old daughter here at home and I cannot open my mouth and say anything to her without her having an attitude and I feel like my husband just don't understand I am also going through menopause and all I want to do is cry,scream, I have no patients I bite peoples heads off and do not mean to I have turned into a total monster and I don't know what to do. My marriage, My Mother In Law, My daughter, My grand daughter, and I have 8 other grand kids and 4 other daughters I have no time or patience for I feel like every ounce of happiness has been sucked away from me and I feel like I have no way out what do I do How do I cope, How do I smile again and laugh and enjoy anything all I do is cook,clean,homework,