Anxiety in the elderly and my own fears

Hi, new here. I'm 37 and live with my 86 year old grandmother who adopted me. Last year, after reading news about the tsunami / nuclear plant disaster in Japan, my grandmother woke up and became very agitated, to the point I couldn't get her to settle down. She had delusions and I took her to the hospital. I was so scared because I had never seen her this way. She has always been an activist for her anti-nuclear beliefs, but never so agitated and confused. I have had anxiety all my life (since childhood) and I couldn't handle the stress of seeing her being held down and given meds to calm her in the ER. After a few months, she seemed ok again. During the past year or so, we have had 5 close deaths of family. Then, she had another episode last month. This time, she woke up crying and telling me she was getting messages from God. She hadn't been sleeping, and was up most of the night reading her Bible and other religious books. I also couldn't sleep, because she kept babbling all night. I again took her to the ER and after a few days she started to calm down. The doctors changed her medicines for blood pressure and gave her Seroquel (low dose 12.5 mg to help her sleep). It helps calm her, but I am anxious about her being on this med because it states that there is an increased chance of death in the elderly and many people have had bad withdrawals from this drug :( I feel that I can't leave her alone because I am worried that she will have bad side effects or another episode of being highly agitated. I also have a driving fear. (I don't drive out of town, and rarely leave the house unless we need groceries or dr. visit) I don't really have anyone to talk to and I hate letting my grandma see me upset and anxious when I help her. She gets upset when she sees me upset. She also hates when I keep asking her if she's ok.
She tells me that she feels better, and I should take care of myself now, but I can't shake my fear of something happening to her or me. If something happens to me, I won't be able to watch over her. A doctor has just prescribed me Buspar but I haven't filled it because I am so afraid of the potential side effects. I don't have any close family that can help me, and only 2 friends who are too busy in their own lives. I also fear for my future because I haven't worked in several years since my grandma has needed help at home, never went to college (because of anxiety/driving fear) and I don't have any of my own income. My grandmother pays my bills for helping her. I am applying for disability for my anxiety and physical problems with my legs and feet.
My grandmother was never diagnosed with dementia or Alzheimer's and she has had many tests, which didn't show stroke, blood clots or tumors.
Any advice is appreciated. Thanks for reading and letting me vent.

Thanks for replying. No, I don't have anyone who can help me except for a friend of ours who comes in once a month to take us to lunch. She offers to help sometimes but she is too busy helping her church and others. Another friend can help drive sometimes if we need to see a dr. out of town, but her husband is having heath problems. My grandmother can cook, take sponge baths, and get to the bathroom on her own most days. She needs some help dressing because her hands are stiff from arthritis and she had shingles in her arm and hands in the past. After she was released from the hospital, she had some home health nurses drop by for 2 weeks but they said she was well enough for them to stop services. Grandma seems much better, she can talk more normally now, (isn't babbling or talking silly) but she does get a little irritable at me sometimes. (Her medicines also can make her constipated) She hates it when she thinks I am watching her to see if she has symptoms or any problems. She will ask "Don't I look ok?" I know it is my anxiety taking over, but I was traumatized seeing her act so unlike herself when she was delirious / delusional. I am hoping the episodes were only temporary (depression or anxiety) because she had been under so much sadness and stress with the family deaths. She underwent many tests last year and was evaluated by a therapist and neurologist. This year, she had xrays, and was seen by another therapist. I talked to my dr. who thinks the Seroquel may no longer be needed, but her dr. wants her to stay on it indefinitely and her next appt. is months away. Her son lives in another state (5hrs away). She likes to watch tv and news, but I try to limit things she watches so that she won't get upset. However, she tells me she's fine and gets aggravated when I won't let her do something. She wants to be as independent as she can be, & tells me to go do something I like, but I have lost interest in my hobbies because of worrying about her. My main outlet is looking up things online.