Help! I just found out my fiance flirted with other women while we were dating!?

[136]

Hi guys. So I am in need of advice and help

So my fiance and I got engaged in November 2013.
We started "officially dating" August 2012. (But i have known him for 5 years before that)
I trust him with my life. He makes me the happiest ive ever been in my life. I love him more than anything.
But I just dont know what to say or do, i usually avoided relationships in the past so i am not good with talking about issues with ppl in general. And he never struck me as this type of person.
Anyways, he left his fb wide open on the tablet last night. And i have never "snooped" before in any of his personal things. I had a gut feeing and went with it.
In september, october and November of 2012
He has messages under archived. Talking with women saying
Legit quotes:
"wow your so sexy"
"Your so beautiful"
"Lets go out tonight this is my #..."
"Hi my name is gussie. I live in ____ and I wanted to introduce myself to you because your so super hot and in case we ever cross paths you will recognize me"
And etc...

After those msgs. He never wrote to any women after that. I couldnt even process how he could say this to me. He is from turkey, i have been learning turkish since we dated. Made him his home foods. I have done alot. This is like a slap in my face. And i feel so stupid.

What do i do??
I dont want to end things with him. But i dont want to be with someone i cant trust.
Please any advice will be great...
Thank you <3