You are already strong. You can do this. It's tough, and you are fighting a hard battle, but you can DO this.
Just take it one day at a time. Don't worry about months, or years... just one day, one HOUR at a time, if that's what it takes. I also strongly encourage you to see if you can find a support group for caretakers. You need to take care of you, too! You can't take care of her if you aren't taking care of you.