Things evolve fast. I could be in your shoes very soon. My mom's health (no other family) is plunging. Her epileptic ground gets worse, resisting to treatment and now experiencing side effects out of control (scary memory losses short and long term). Yesterday morning, she didn't remember her email, how to use the phone, or some actions 5 seconds ago selectively, and crying over realising the new fact. I might have to move over to take care of her unexpectedly.
I always had this issue taken into account and postponed due to it, with complete guilt of letting her behind facing old age, wanting to leave while she's sane so she can cope while rearranging a support system around. Now the dilemma reverses while getting clearer and I don't know how I will react if it turns out I pity her health state.
Back to you OP. Life teaches loving parents how to let go of their children. They have a complete picture of the hardships of life. She's prolly grateful of the attention you've handled her. I'm guessing that if your death shocks her with surprise, she will still find a way to forgive your act in the corner of her mind. Old persons carry a philosophical background with them and can understand many things with empathy. Since it's not like she will be alone, it's up to you to decide. You're not a bad person, this thread shows off. When the time comes you have to think about yourself, there's no blame to take imho. Even the sun you curse at won't take the blame when it'll die on us. There once was love and care. It takes 2 beer to remember and 3 to forget. Your mom will survive you, not in the best conditions maybe, but she'd wish you the best. A mutual understanding will last if/when you really have to give up