Relationship Problems!y?

Hi! I am desperate for help!! sorry if this is long this is the only thing I think that will help. Okay so my boyfriend and I have been together for 4 1/2 years were in our early 20's and he went to school away for 6 months and somewhat had a fling with another girl there it hurt me it may not seem like a big deal to some but it crushed our relationship he dirty danced with another girl the first week he was at school and was extremely upset did anything to win my heart back. He totally erased her from his life and won my heart back! We moved in with eachother after his training at school was done and he proposed to me months after living with eachother and only 2 months problems kind of started up again.. first of all I have problems with the trust thing we are working on it.. but he kind of crushed it again. At work he talks to operators on the phone and the guys at work bugged the hell outta him for sounding like flirting but he was really just being nice he is the type of guy that gets along with everyone and could kiss a girl on the cheek and it wouldn't mean a darn thing! So this girl he was talking to on the phone and he has to phone in and tell i am off shift and she said okay i am going on my break now here is my cell phone number if you want to talk to me. Well I was sleeping when he came home and he texted her all night because he said he couldn't sleep and he was bored so he texted her.. well in the morning he told me he talked to her cuz i asked him why he didn't come to bed. and me being snoopy i know its horrible i need to trust him but I felt like something fishy was going on and i checked his cell and everything was deleted and he said the whole inbox was full so he deleted it. a few weeks later he had to go to training again and she works there right when he got there he went to go meet her and after that they started to become friends and he asked her to go out for supper and bought it for her.. then the next day he asked if she wanted to go to the movies and she did and he bought the ticket for her cuz she drove him but they went with other friends and he sat right beside her. The next day he went to the bar and he lost his key to his hotel room so he slept in the place she worked and he asked her to tuck him in??? I always do that and he has only knew her for 3 days just a little weird. and she kissed her hand and put it on his head. He also sat right beside her on the couch at work and played games with eacother on ipod and they played this love test thing were it shows how you are feeling at that moment. and it said it was like flirty mood.. My fiancee admitted that she was attractive.. same interests and they had a really fun time. When he was coming home he phoned her to tell her what a great time they had but he didn't phone me when i was trying to get ahold of him. She is getting in the middle of our relationship and he feels guilty about everything he did with her and he doesn't want to end the friendship with her because he said that it is just a friendship. Then when he knew how much it was affecting our relationship he said i won't talk to her anymore. Don't you think he would've broken up with me and wouldn't of told me all this stuff if he was cheating? If he was cheating he wouldn't kept it to himself! His job is super stressful and I will never understand it some things are confidential and he can't tell me she is kind of in the same field and there the same age and he doesn;t have anyone else at his work place the same age there all way older than him. I phoned her up to say I am sorry if i seem like i am jealous and I am sorry about that because from I delt with in the past and she is like I totally understand I been though it before and she dearly loves her boyfriend. I figured it was all my fault because its like everygirl he talks to i get jealous when I don't know them. But he told me not to blame myself that he shouldn't be doing that when he is engaged. He feels terrible.. I told him everyone flirts to an extent... it just seems so fishy? My fiancee also told me her boyfriend and her werre having problems and then they were good and then he was going to try to hook her up with one of his buddies when he was there but then he was the one always sitting beside her. I was thinking to go home to let him think for awhile he is more overwhelmed and feeling guilty about things and doesn't feel like crying even when I do.. Just because he doesn't cry doesn't mean he is sad right? He always gets really upset but I think his job made him tougher he sees hard stuff everyday and I dano he balled his head off last time only cuz he was gone for 6 months and only saw me 5 times but we held on. I told my fiancee that I don't want him to break off the friendship if he has someone to talk to but there is me he should be able to talk to me.. He doesn't want to make me here those types of awful things he deals with work and rather tell someone hears it everyday. I asked him what he t