His emotional affair with his ex (a year ago)

I just found out my husband was sending "I love you" and "I miss you" emails to his ex while we were dating. These emails are from May and June of 2016. They exchanged nearly daily I love you's via email for months. We'd been dating for 7 months at that point. I knew nothing about it at the time and things got very hostile between them shortly after their last email exchange. It's been fairly hostile since then because she's a psycho.

We got married in December 2016. I'm currently 13 weeks pregnant with our first child.

I feel so betrayed and so devastated. I feel like our whole marriage has been a lie. How do I trust anything he says? What do I even do now? Is martial counseling even worth it?

I was so crazy in love with this man. Everything, with the exception of his ex, always fit so perfectly... or so I thought. He's always told me I was his soulmate, but how do you have an emotional affair and hurt your "soulmate" on such a horrific level?