This People magazine article lays out some more details, but in 2015 Ravenel "allegedly" sexually assaulted his kids nanny in his home. When she was able to get away she ran outside and called her ex-husband and then went to the police where photos were taken of her injuries.
Yesterday Thomas was officially charged and arrested. If you follow the show he wasn't at the taping of the reunion because of the ongoing investigation. It was then later reported he was fired from the show. He claimed he quit. Either way he def won't be back next season and I can't say I'm sorry to see him go. Hope the nanny gets the justice she deserves.