I don't know know to feel (PLEASE READ)

Lately my fiancé has been very secretive. Putting passwords on his phone hiding things from me working later than normal. I'm sure you can tell where this is going. I confronted him two months ago until now I kept saying you're being secretive, are you cheating on me?, is something going on I should know about? All he would say is "you're crazy", "you're insecure" and "it really hurts me that you don't trust me". Then eventually I started thinking maybe I am crazy... maybe he's right. Until yesterday at 3am I woke up to pee. He was dead asleep and I took his phone typed in the password I saw him put in a few days earlier and got into his phone. I didn't see anything out of the normal on fb messenger, text, Snapchat nothing except him talking to his friends. I thought I need to apologize to him I am literally crazy. Then I accidentally clicked on a Snapchat from 'Logan'. Let's just say it sure as hell is not a Logan. I went back on text, fb messenger and sure as ever there it all was he has been lying straight to my face about a girl we had previous issues with. I woke him up confronted him and asked why he did it and all he had to say for him self "honestly I didn't think you'd ever find out, and if feeling bad is 100% I feel about 2% bad". Then he started crying I asked if he was upset and he said no "I was saying good bye to the fish in my head." I told him he could either stop talking to her and we could work it out or he could walk or the front door right now and never come back. He picked up his things and walked right out the front door.

The one person in the world I have ever truly loved, truly cared for and would consider my home where ever he is. I in no way feel angry or upset. I feel betrayed and it upsets me thinking I will never be with the person I planned to have future with. But I just have to remember it's for the best and he is no longer the person I fell in love with.