Is this some kind of child abuse? What should I do?

Long story short my husband found out he had a 7 year old that was about to be put up for adoption due to the mother losing him because of drugs.

He finds out, we get full custody and has been living with us for a year now.

We have a 7 year old back then 6. Well I just had the sex talk with him because he is very advanced for his age. I have always kept her mind very innocent as much as I can.

Well after the sex talks he starts crying and telling me that he thinks he had sex with his brother when he had just moved in with us.

He says he would make him kiss him and get on top to rub against each other!

I'm in extreme sadness and I have no idea what to do!

I need help please !