Don't let the crying get to you and try to keep your frustration down. I was a crier too as a child and hated being yelled at. I couldn't help it and it was not on purpose. My DD is the same way and my DH and I always have to be careful to not let her crying change what we are doing.
So what we do is that we do not respond to the crying one way or the other. For example - if she starts crying when we tell her it is bed time we still continue with the bedtime process as if she was not crying. Bath, pjs, brush teeth, story, bed. She can cry the whole time if she wants but usually she realizes it is not changing the situation and she stops.
For discipline we give her a warning, telling her what she is doing wrong. If she continues then she gets time out. We speak clearly to her but we do not yell and we do not hit.
She is the child, let her lose control of her emotions. You need to keep yours under control, no matter what she does.
It is also good for you to tell her that you understand that when you say no it makes her sad, but that does not change your answer. A rule is a rule and your decisions are not changed by tears. Period.
She needs a reliable home where she knows the rules and the punishments and that you are the authority. You can establish this with her without yelling or hitting. Good luck!