Just let your boyfriend give it to her. She certainly sounds like she deserves it. Respect goes both ways. There is only so much crap you should take from your inlaws and you've taken way more than enough. It's not fair for you to have to deal with everything by yourself. He should be taking care of his own mother, not you. He needs to get more involved and perhaps skip the gym to take care of you.
You daughter needs YOU not her grandmother. You are doing all of the right things. My nephew was a colic baby and we did the milocon, gripe water, and we even went to soy milk, then eventually our savior milk was Nutramegen, which is pre-digested milk. It reallllllly helped with his colic. May want to ask her dr. about it. It worked like a charm. He still had his moments but it was like 70% better which helped a lot. I stayed with my sister for the first 5months of his life to help her with him. So I know about sleepless nights. My sisters mil is also over bearing but my sister gave it to her, so she backed off after that. Either you give her a piece of your mind or have your b/f do it, afterall he needs to be responsible for his own family.