I developed a new appreciation for my MIL once I had a son myself.
I doubt she set out to annoy you and she'd probably be mortified if she realized that's how you felt. She was probably just excited and wanted to help out.
Just speak up for yourself and set limits as you must. Set the tone how you want it to be early on.
Others may disagree with me on this but I don't think this is a road you really want to go down. Don't make him pick and choose or downplay her role, which he could come to resent. Surely there's room for both of you in his life. Your bf will appreciate your efforts to get along with her.
My MIL is a wonderful lady but we don't always see eye to eye on everything. (Shocking, no doubt!

) I'm sure my DH would say the same about my mother as well (and she lives with us so he has a harder job than I do at times). Despite this I have a tremendous respect for the blood, sweat and tears that MIL put into raising my DH and the love she has for him. I also see the love he has for her and his father and I am grateful that he has that as it just makes him a more loving person to me and our children in my eyes. When I think of it this way it's kind of hard to find fault. I do believe she always means well even if we see things differently sometimes, and she has told me that she appreciates what her son and I have together, so it's good to sit and have these conversations if at all possible. (Though I appreciate that my MIL is someone you can do this with and know that not everyone is.) Maybe you could just go out for coffee or something sometime - you could wind up seeing her in a different light.