Sounds like things are moving right along. It seems to me that maybe your MIL wont ever be your best friend, she will have to eventually see that you and H are happy, and what more could a mother ask for than her son to be a happy and fulfilled H and father? I would say just keep on keeping on and hope for the best, besides, if she cant get over it, thats her problem, you arent M to her!
I would expect a long haul regaining her trust, and your probably already ahead by just acknowledging that her feelings are valid and she has the right to have them. Your right, DB her! It works in all kinds of relationships!
I guess I gave the wrong finger to the wrong man...