This is probably the ONE THING in all of DB where there is unanimous consensus. When she asks WTH you're doing, say "I decided there's no reason I shouldn't sleep in my own bed. I'm more comfortable here." If she says that she's not comfortable with YOU in there, calmly say "I understand, but you don't have to leave. But it's your choice -- I'm staying here."
"What is best for my kids is best for me"
Persevere = happily being patient over a long period of time