She started to tell me that snooping was her major issue and that she felt controlled and belittled by it...The last time I confessed to snooping you said don’t worry honey its ok then you left that night.
She just told you something really important here. I know it is hard, cause I was compulsively snooping for awhile, too, but I think you really have to stop. I think it would be a meaningful change to her.
I think this also may be partially why you don't want to give up paying for her phone, because you can see who she is calling/texting?
My advice would be telling her you want the phone transferred into her name/her pay for it to indicate that you are no longer going to snoop. You could tell her you don't want to snoop anymore, so the phone bills will be hers now. You're getting the added benefit of letting her stand on her own two feet at least a little bit.
The more she feels you are trying to control her, the more she is going to run from you. That's a good mental image to have when you feel the urge to snoop, is that she is running further away from you every time you do.
It is in the shelter of each other that people live.--Irish proverb