Found out that my dad is a child molester?

my dad and mom were arguing yesterday. when my dad left to go to a hotel, my mom started to talk to me. she told me that my dad molested my half sister when she as 7-12. i called my sister to verify if it was true. she said it was. she is now 27 and lives 3,000 miles away from me, my mom, and my dad. she said that my dad had with her. i am a 16 year old girl, and i dont know how to fathom this. it hurts. u think you now stuff, and you really dont. i dont know how to act around him, i cant even look him in the eyes..