Just remember that some people are just PLAIN IGNORANT. That may be the case with you MIL and BIL or, they may honestly be torn in their loyalty to your H behind the PAST difficulties between the two of you that he's shared with them.
Often, we go to our family to dump our pain and although WE eventually bounce back from it, the pain we've dumped in their lap lingers because they love us and don't want us in pain. So even though you and your H are working on fixing things...his mom and bro may still be harboring resentment for the pain that your H has told them YOU caused him.
You sort of have to give his mom and bro a pass on thier ignorance because 'blood is thicker than water'...and some families just don't know when to mind their OWN business and just be happy that the their son/daughter and their mate are working things out.
Don't worry about them for now...just concentrate on ALL the great growth that YOU and your H are now experiencing. T2