First, let me say this has nothing to do with Dwayne and I.
Here goes.. I'd like some completely honest opinions and/or advice.
Let me give some background info: My sister is 29 years old, she has been with her fiance for the past 5 years, they've had 2 miscarriages in those 5 years.
Now, here's the problem: I think she's cheating on him!

I know, this is a horrible thing to think, but she's done it before. I've personally caught her before too. I was like 16, got into her email and read emails from this guy, I copied and pasted them ALL and sent them to her fiance. Who, didn't believe me, and told my sister I was trying to break them up.

I could care less if they were/are together, but I think he deserved to know that she was emailing this guy back and forth. I won't disclose what was in the emails, but she was clearly cheating on him.
Maybe I'm just being nosey here, but, usually every night I see her writing down phone numbers. Right after she writes down these phone numbers, she will then go to her room and be on the phone for hours on end. With people, who I KNOW are not her fiance. (He works night shift, and doesn't wake up until 7pm, and doesn't call her until 8:30pm. This has been the ongoing thing for years now.)
I don't know what to do, I think she loves him, I think she wants to be with him. But, I know right now, he's annoyed at the fact that she got pregnant when she told him she takes her pill everyday. He's been distant ever since the miscarriage too. Something tells me he doesn't want to be with her though, things like, when his mother says things to my sister that are rude, he doesn't defend my sister. Also, he has no problem telling her what the guys at work say about her.
Help?