ANSWER:
If you’re going alone with him, this is not permissible at all because he’s a non mahram to you and Prophet salla Allahu Alaihi wa sallam said that the the brother in law is death!
You must observe complete hijab in front of him and never chit-chat, hang out or socialize with him, not even in family gatherings so there’s no question of going out alone with him.
https://youtu.be/OvPMHo5SGZ0