My husband cheated with my 17 year old sister

Ava

So just a little back story. I found out on Sunday that my husband who is 24 has been having a sexual relationship with my 17 year old sister. I found videos of the sex and naked pictures she took of herself on his phone in his recently deleted album. The heartbreak and betrayal I feel is unreal. He has grown up with my little sister, basically helped raised her. Has lived under the same roof as her since she was 10 YEARS OLD. Am I wrong for wanting to keep the kids from him until we go to court? His family is acting like the only thing he did wrong was cheat. Not the fact that he’d been having sex with a 17 year old who LIVES WITH US for months!! My sister said the sex started when she turned 17. Which was in MAY. She is currently in a psych ward. Not to mention that he hasn’t even tried to apologize to me. I just want to know if I’m doing the right thing by keeping our 11 month old daughter, and 3 year old son away from him until we go to court. I’m just trying to do the right thing for my kids.