My mom was the most non-confrontational person I know. Once we were living in Houston and she arranged to leave him by pretending we were going on vacation to Utah, then have my grandpa call him once we arrived to tell him we weren’t coming back (he didn’t want to come with us).
Well he sensed that something was up - he said he would come with us for a few hours, then find a flight home when we came to a big city. Instead he pretended he was really sick, and came all the way to Utah with us, and still really “sick”. Finally after a week or so my Grandpa talked to him about it and made him leave.
So when it happened again we knew we had to carefully plan out her departure. My 2 older brothers coordinated a plan with her bishop. The bishop visited them at my mom’s apartment and convinced stepdad he needed to let her go - the next day my brothers who came to town secretly, picked her up and drove her back to Utah.