I want to tell the truth

by Ladybug

I've commented on this site a few times encouraging others that honesty is the best policy, and now it's time for me to the my own advice. Back story: I was born after my mom had an affair. Her husband who was raising me as his own cheated on my mom later on, and their marriage sadly ended in divorce. I just reconnected with one of my dad-who-raised-me's daughters from a second marriage. We didn't grow up together, but I would visit my d-w-r-m and his new family from time to time. His daughter is about 10 years younger than me and now has a family of her own. Our dad passed away years ago, and we didn't stay in touch much. Before we really start building our relationship, I want to share the truth with her that I'm pretty sure her neither of her parents ever mentioned- that I'm not her biological sister. I don't want her to be mad at her mom/my step-mom, who I guess just wanted me to be considered as part of the family, which I can appreciate; but I also want our relationship, if we continue to build one, to be authentic and without secrets. This information has played a significant role in my personal development, and I'm telling myself that I can't control how she will feel about the withholding of it over her lifetime by her dad and mom. I am different in looks and talents than my siblings, and I bet even she feels it deep down, but this info. seems a little much to bring up over the phone. We live far away from each other. What do you all think? Ideas?