Hi 2Times2Many - I admire the way you are traveling this road.
Of course your h is nice and comfy! He's left things in your very capable hands.
My advice is to listen to your inner voice. It sounds like you feel helping him out with the wiring of funds enables him to cake eat. In my personal opinion, I agree. Even if there is no OW, I feel this is his responsibility and he should deal with the reality/hassles of wire transfers.
As for the calls, in my opinion I would bow out of those a bit. You say yourself you are not comfortable with the current sitch. And I can see why. You can see if he reacts and if so, how. I would do this carefully as he will pry as to why you weren't available. Personally, I would 't even say you have nothing to update him on. Whatever you say to BIL will get back to h. So what message do you want slipping to h? Maybe try saying to BIL: "I won't be in today as I have plans." H will call in and someone will say you aren't in. He'll probably ask for BIL then, maybe? If so he'll pry. Or maybe you should go away for a few days and say to BIL "I'll be out of town" and nothing more.
Just my .02.
Me 41, H 47, M 15 yrs, S11, S13 BD 1: 11/4/14 we work on it; really I pretzel myself BD 2: 3/31/15 H goes down to "dorm room" 8/15: H back to MBR 10/15: H back in dorm room 1/18: H files, now divorced