You weren’t wrong to file. You have a better chance of getting a fair settlement early on, when he still might feel a shred of guilt. Also, the more reality intrudes on his fantasy life, the better.
I don’t recommend dating like your SIL, but that was probably part of what caused your brother to snap out of it so quickly. That’s why I recommend giving the APPEARANCE of dating, with plausible deniability. “I never told you I was dating, I just told you those flowers were from a friend”. He noticed it, and I guarantee some part of him wondered about it. Keep it up. They like to think we’re just waiting on a shelf as Plan B in case they want to return - it unsettles them to think we might not be there. And men being possessive, they also feel upset at the idea of another man bring with you - even when they’re living with another woman!
So hang new fancy lingerie up to dry in the bathroom, leave two used wine glasses out where he might see them, let him come shovel your snow do he has a chance to see these things. Be mysterious about where and when you’re going.
Then go about your life and imagine a fabulous new future for yourself.
