My fiancé and I have been together for almost 5 years... I recently found out that he's been texting his female coworker for over a year... When I first found out about them texting I simply asked that he wouldn't text her anymore he said he wouldn't and I let it go... A couple months later he told me to text my aunt on his phone while i was texting her a message came in from his coworker and it was two picture messages came through and they were referring to sexual things... I was so angry that he lied to me about texting her... I told him how I felt and he deleted her contact info right in front of me.. Last week his phone went off and it was an unknown number... Luckily it was his friend but when I checked his recent contacts it showed that he was messaging someone named "Diego"... There were no messages or phone calls in his log.. I know all his friends and coworkers names and I've never heard of someone named Diego... A few days past and I checked his phone again... Diego was the last person he had talked to but there were no messages... I knew he had deleted them before he went to bed... That night I couldn't sleep so I looked through his phone.. I took the phone number entered it into mine and searched all his social media accounts but I couldn't come up with anything... I finally checked snapchat and the coworker I asked him not to talk to was in there... He didn't deny that he was talking to her but said there conversations were strictly work related... I checked our phone records and he was texting her everyday for an entire year... The texting quickly escalated into phone calls that lasted about an hour... I told him I was going to ask our provider for a text print out and if he didn't want me to see something he should tell me... He said he talked to her about our relationship, wedding, problems and asked her to go hiking with him on the weekends... I don't know what to do... I know I shouldn't blame myself but why is this happening... Should I not marry him??