I forgot my cell phone at home while my boyfriend and I went to school and my boyfriend's sister snooped through my phone and found that I was talking about her... now she is causing problems for me and my boyfriend... she wasn't supposed to see any of it... can she be charged?

No, not that I can see.

No there are no laws covering that. If you don't want your phone snooped, then always keep it with you or put a password on it.

And what do you think your boyfriend would say if you tried to put his sister in jail?

The other thought is to remember that what you put out there lives forever. Apparently telling people your problems with her live and in person wasn't enough so you put it in texting. Not a smart idea.

She's probably going to post any time now asking if SHE can sue YOU.