I'm sorry bro, but you have to ask yourself, do you really want to live like this? Constantly having to check her phone, having a friend spy on her, worrying about what she is doing every time she is late..I'm not at all telling you what to do, but like I said you need to give this some serious though, if she has done it before...
just don't want you to get played brother..your to good of a guy.