<human>: Background: I'm 27/F and my husband is 29/M. Together for 4 years. 

Recently, I came to the realization that I had been holding on to some very old feelings of suspicion towards my husband, and that it was time to let them go. I approached him gently one night with a heart to heart where we could reveal anything we had been keeping from each other with no consequences. 

In the first year of our relationship, I suspected that he had cheated on me emotionally and physically with his ex-girlfriend. While we were not very serious in this first year, we were definitely not seeing other people, and I made it clear that I did not trust her, and that their relationship was problematic. 

During our discussion, my husband revealed that he did on a few occasions (about 5) sleep with this woman. In addition, they carried on a flirtatious, emotionally-charged caring and loving relationship (I knew they were talking, but not like that). 

The problem I am having is recognizing  how blind I was to what was occurring in front of me. My husband feels awful for hiding this from me, but I understand why he did it (I had some secrets from him too, more minor… but still). I am not mad at him, I am just trying to grapple with this new reality and use the pain I am feeling constructively. 
Any advice?

Can you condense the text into three sentences or less?
<bot>: Having a hard time grappling with emotions stemming from recently finding out that my spouse cheated on me during a non-serious time in our early relationship.