The Sandwich Generation

So when I was in college we learned about the "sandwich generation". Although I am technically not the Sandwich generation, my mother is...and I help out. For anyone who doesn't know, the Sandwich generation are those who have not only raised their own kids, but are now taking care of their parents. There are different reasons why people choose to have their parents live with them. My mother's reason was 2-fold. First she couldn't bare to see what was happening to my grandmother mentally when she was in a home and secondly, my sister worked for my grandmother and she needed the income. In all of the craziness that occurred last year with my grandmother needing 24 hour assistance, I took on part of the responsibility of helping. In the beginning, and for about 6 moths, it wasn't so bad. I was more sad than anything. Even though my grandmother is in her mid-nineties she was pretty self-sufficient before she broke her hip. Now she is like a toddler. She has dementia and has crying fits and gets angry easily. At first I was here 5 days a week for a few hours a day and now due to my full-time job I am here 3 days a week in the afternoon. In the beginning I would sit with her and do her nails and we would joke around. Now it is getting rough. Everyday she gets upset about something...and usually this something is really nothing. Today I came over and she was perfectly calm watching some Lifetime movie with her helper. (As a side note, I do not know what we would do without the amazing ladies that stay with her at night. They adore her and really take amazing care of her.) The show ended and I changed the channel. For over an hour my grandmother has been yelling at me and crying. She yells to me to get out, or leave her alone...etc. This is not the first time or the last time this will happen. I know this is a tough situation to be in for all parties involved. I am not trying to say that I don't love her or that I wish I didn't have to help. Neither is true, I just hurt. It hurts me to see her mind going. It hurts me to see her upset and know that there is nothing I can do to make things better. I try to reason with her and ease her unhappiness, but nothing registers correctly with her. It is aggravating and wearing on me, but I try to hold it together. I try to do what I can, but some days I feel so bad. I feel like she hates me and I don't know what I did wrong...but I know she doesn't know what she is doing. I know there is no reasoning, I just have to leave her alone and let her calm down. The more I try to help when she is like this the worse I make it.