It doesn't have to be extremely difficult to stay living under the same roof. Everything depends on the individuals concerned, the state of their emotions and the people around them.
Both my exes were abusive in different ways but the day-to-day aspects of the post split house sharing were surprisingly easy. In both cases, there came a point very soon after the breakup talk when my feelings for my H changed. The feeling of grief stopped and it was all about getting stuff sorted. Even with the unhealthy power balances, there had obviously been enough friendship & shared interests to build a marriage on in the first place. And we knew each other's routines and so on, so it wasn't difficult to juggle things around a bit to suit the new relationship.
XH2 had done such a good job of painting me as an irrational loon to his mates, they couldn't understand why he was OK about sharing
I left the explanations up to him.