Please guys, I need ur honest advice...I'm a Nigerian but live in florida.

My fiance recently started a new job (after being laid off since November). I really was starting to think things would be looking up in the romance department. Well because he has hidden things from me in the past I am now in the habit of randomly searching through his email and phone. For the most part I don't find anything and what I do find could be taken in other ways. I went on his gmail and checked his web history and found that he spent a lot of time last summer looking at pornography on the web (while I was pregnant with our daughter). I have not said anything about this but I then went onto our phone bill online and was able to see numbers that he texts or calls. I found one that I did not recognize and proceeded to go through his phone. (Please keep in mind that this is not like me at all but things have been off between us and not for lack of me trying (I own nothing but Victoria's Secret nighties and undergarments) he just has no interest.) The number was from a girl at work. He initiated the conversation and was just asking her about the new job as they met in class for the job and then proceeded to be sent to separate job sites. After a few texts she mentioned that they should "get together" on their day off together (Tuesdays). He said "Cool" then sent another text saying "Yeah my house is pretty cool...blah blah blah". I was upset that he didn't turn down hanging out with her but I figured I would wait and see. Nothing was texted for about a week then they had to return to class again for lecture on Meds. After the first day back she texted him again so I finally called her (maybe a step too far?) She seemed to understand why I was concerned and said that in all actuality she would have been treating the other woman much worse than I was treating her. Shes also said that all he does is talk about me and our daughter and that it's just a friendship. At the time I was too nervous to really think straight but I asked her to please not tell my fiance that I had called as it would just cause problems. First thing she does Monday morning is tell him that I called her. Well he flipped. We have spent the last two days arguing over this because I really do not see the point in this "friendship" with her. According to him they have nothing really in common. But it makes me wonder why he would even try to get her number and text her in the first place? And all she is proving to me is that she has no respect for my relationship with my fiance. To me texting another woman's spouse is crossing a line unless it's absolutely necessary, but talking about getting together is definitely crossing a line. I am offended that he would even think that that's okay and that instead of clearly stating "no" or "Maybe we could double date" or any other number of possible ways of making it clear that I should be included he just said "Cool". It's as if he was leaving the door open for the possibility. And if he didn't really care about this girl the way he says he doesn't then why would he want her number? We have been arguing over her and it's putting a huge amount of stress on our relationship. He has become someone that I am completely unfamiliar with. He has said things that are hurtful t me which is not in his normal character. I apologized to him this morning and he said that he accepted my apology but did not offer one of his own for being so careless of my emotions. He is usually so sweet and tender and I just do not know what is going on in our relationship right now. I am so hurt and confused. The best part about all of this is that she LIVES in our complex. So it's not like they would have to go very far to meet up if they wanted. This entire situation has made me extremely uncomforta