Poor you, it sounds like a bad case of sibling rivalry aswell as the abuse factor,How about you keep them apart more, let them play and do their activitys in differant areas and make them stick to that rule,if they wont give them time out ,sit them on a chair seperatly and say to them they must stay there till they stop.I think some counseling is called for regarding the Abuse,Possibly the 2 boys have some jealousy issues, how does the 7year old behave with the 5 year old, check out quietly the Behavior with each other.As there is a problem keep them away from each other ,Have they got a room each it would give you some peace if they went into their own space. Does Dad get involved with them how about he does some Games and sport with the 7 year old and you read or play games with the 5 year old, one to one with each of them, Get Dad involved and do guy things with them.Good luck I know what a battle it is my Daughters still have sibling Rivalry and trust me they are years older than yours!!!