break in means 1) to enter house or building by force in order to steal something (e.g. Someone had broken in through the gate and stole our car.) 2) interrupt (e.g. The boss broke in to report of the annual sales performance.)
break something in means to familiarize someone something with a new (e.g. I bought these shoes yesterday. They should be OK after I break them in.)
break into something means enter with extra force or start doing something (e.g. The police broke into the building when they saw smoke.)