How does one overcome regret for a difficult life decision?

I had my daughter (Leah) on March 8th, 2005, which was the same day I gave her up for adoption. It is an open adoption and I receive photos and updates every few months. An annual get-together is also allowed, however she is currently living in a different province. I haven’t seen her since the day she was born. Her adoptive family is great and I feel that they are doing an amazing job at raising her, and I’m sure they can provide so much more for Leah than I could. But ever since I gave her up, I have never stopped regretting my choice. It tears me up on the inside, and when I get new photos of her, it’s like giving my baby away all over again. I thought the pain would lessen with time, but it seems to be getting worse with every little part of her life that I miss. I know it sounds terrible, but I almost feel like it’d be easier if she had died. Just knowing that she is out there somewhere, without me, kills me. I was pushed into this choice by my parents, my friends and my boyfriend at the time. I wanted to keep Leah. Now I know I will never truly be her mother. How do I learn to get over this?