I just stumbled across your blog, and that poem has put a really big smile on my face. It takes an awful lot of strength to write something like that, and even more to do what you're writing. You've inspired me, thank you.
I can relate. My half-sister's father is the man who abused me and every time I look at her, I see a little of him. I love her, we're really close sometimes, but she's his and that haunts me. I completely get why you get the anger and the resentment when you see your half-siblings. -hugs-