Hubby is mad at me for what I said about MIL - thoughts, did i over react?!

I brought up the question of what else we should get my MIL for her upcoming bday this week. Hub said "we get her more grandchildren for her bday". Then i instantly responded w/o thinking how it came across: "they are MY kids, not a present for her. We get her her OWN present, just for her, on her bday. I have some gift ideas" .... Well the whole "my kids thing" really threw him off and he gave me the silent treatment, i feel so bad because he rarely gets mad 😫 but heres the mini back story to my dumb knee-jerk reaction:

That remark triggered me for 2 reasons - 1. He never wants to put any thought into what to get her for her bday, I always end up getting the gifts and he knows it irritated me. And 2. My MIL is so involved in my babys daily life to the point where I have a huge anxiety about the thought of my children seeing my MIL as the "parent" (she says things all the time like "i cant wait until you have more kids so i can steal Kira (our daughter) while you take care of the next baby" or "she is the love of my life, the love i feel is incredible, i dont know if you know what I mean")... Of course i know what you mean I AM HER MUMMY 😫

Was i totally out of line guys?