Wow, what patience, I admire you, I'd probably start shaking and then lose it. I'm 49, have a little more patience than many years back or have learned the art of tuning out certain stuff, helping me avoid confrontation.
But I am no pushover,when mother-in-law tries to be bossy, cause she is controlling, her husband use to let her get her way,jokingly would refer to her as "the boss", guess what, she isn't mine, no one is.
I don't know what to tell you to do with this stuff, but it is cool you didn't lower yourself to her level, and kept cool. She may have been hoping she could of provoked you enough, that you'd come out with something to help her validate her fabricated fantasies about you.
I think you also need to talk with your bf and make him understand you deserve respect too, maybe you can have a talk with him and then have a talk with her and maybe include him too.
On the other hand if she is one to think her way or no way, it may be a waste of time, once someone is certain they are always right there is now inning with them.
When things settle, try the conversation approach if the opportunity is there, even rehearse what you need to say,to see how it comes across.
Lots of luck with this, and again I admire you for not losing it/

DE