you should rly tell your siblings whats going on sooner than later because your mom should probably take him to court soon and try and get custody of the kids and try and get proof of him cheating like print out the messages off of facebook to bring to court also just in case they ask why you came to court and then to prove how it could be true. and have proof to discribe the situation of how you would have to live if you lost the house... hope that helps a little!