How would you feel if this was your fiance?

People please give me your honest (and please don't be mean) opinions about this situation. I'm trying to get input to see if im doing the right thing. My fiance whom I have been dating for over a year now and I are about to get a place together. (Like in four days). I have called the whole thing off. My reason is a girl he has as a friend and has had since the start and that we ve argued about from the start. I can't take it anymore. His reasoning is they've been best friends for ten years and i've tried to respect that. My reasoning is he has slept with her, she does things like call him at 2am and try to buy him presents, and certain ring tones he has set to her (ones talking about are you lonely tonight 'cause i'm lonely to). He says sleeping with her is in the past, they are friends so she wanted to do something nice, and it's just a ring tone i'm trippin. All his friends say she has a thing for him (she has a boyfriend but he is terminally ill) and that he's her back up (her relationship has been four years long. she cheated on her boyfriend with my fiance). He says while that may be true but he doubts it highly he wants nobody but me. While he no longer sees her face to face (that I know of anyways... I have my doubts but I am a little paranoid sometime) and has cut back on the amount they talk they still do things like last night. She called him at 2am because somebodies mother died or she thinks somebody's mom died and she was trying to figure out if Tommy knew who it was. I'm saying though... it wasn't even somebody close to them... we both have to work this morning and I not only have to work all day but have school all night... am I wrong for thinking this was inappropriate and perhaps not her motive for calling? Why did she need to know who ped away at 2am its not like you're going to call the family and send your condolences at that time? Or am I just being overly paranoid about this occurrences and dwelling on the past? I would really appreciate every ones opinions regardless of whether they agree with me or not? I want to know how other people would feel/handle this situation. I know in the end only I can decide whats right for me but i'm still wondering...