BOTH my step kids are making poor choices

EDIT: Thank you ladies SO MUCH for your advice. Just fyi, my daughter LOVES church and had accepted Jesus and been baptized at her own request in the last year, which made this come as an even bigger surprise. I am slightly considering bringing this up in our tiny, close, supportive Bible study group. I'm definitely continuing to pray about it ❤ *ORIGINAL POST* I'm disturbed and beyond disappointed. We have full custody of my husband's 14 year old daughter and 10 year old son. Yesterday, got a call from the boys friends mom. On the last sleepover, my kid thought it would be a good idea to take a video of his penis. He told the friend it's ok as long as they delete it 😵 Well, the friends dad found it in the trash on his phone. smh. SO I get my son's phone and we check the history...and find porn. 😠 He admits to the video but SWEARS the porn isn't his. We then realize his (old, smashed screen that his bio mom INSISTED he needs)phone is attached to his 14 year old sisters Google account. The porn was her 😲😳 She has been GOOD lately! Her bio mother insisted that she needs a phone too, and gave her an apple 8. We allowed it since her grades are good and she has been responsible and respectful. After her brother got in some trouble, and we figured out it was her, she finally admitted to it. She feels bad for lying, but said "it's just a little porn" 😠😵😩 My husband and I took away their phones until further notice. YouTube is banned for the time being. No xbox. What should I do about this? Any advice? I seriously don't want to talk about this with my church friends.