two boxers male and female

Question
We just got a new male boxer who is 4 to be a friend to our female boxer who is 2.  The new male growls at every thing jumped on our female and got the crap bit out of him. we are trying to get all used to each other the female is doing good and gets along with every one. but the male does not like even my lil boxer female what can i do, now the male is in a crate and only gets out when all dogs are put up or he has a muzzle on. the pit will live him alone but the boxer trys to start it every time, thanks

Answer
It sounds like you are having a very big problem with dominance.  Some other things to take into consideration at this point which you have not mentioned... Are these dogs neutered/spayed?  If the new male is not neutered already at his age this could be causing a lot of issues.

At this point he is trying to be the boss of the house. While it is never to late to train a dog, unfortunately at the already adult age of 3 it becomes much more difficult.  I suggest seeking the help of a behaviorist/trainer in order to have your new male evaluated.  His issues may be trainable, but there is also the possibility his past treatment has permanently affected his behavior.

For now, i would suggest keeping a close eye.  Keep a squirt bottle or shaker can, can with pennies or anything that will make a jolting noise, keep these nearby in case a fight starts.  Take note of body language.  Do they stare at each other?  Are their tails standing up straight? Dogs should never have a 'stare down'.  Normally dogs will catch eyes and the submissive will look away shortly.  If you have two dogs doing the opposite they are fighting for dominance.  Watch their behavior closely, if you see your male boxer instigating and trying to pick a fight, immediately let him know you are boss, and reprimand him and place him in another room.  Do not let him take control of the situation, if he does he is making himself leader of the house, and this is not what you want.

In the short run, all you can do is take steps to avoid a dangerous situation, and continue to train/correct his bad behavior.  Contact a behaviorist or trainer as soon as you can in order to have your boxer evaluated.  In some extreme cases, past experiences just affect a dog to the point where that behavior is so ingrained in their mind.