Blended "not so" Family ???

let me start by saying we have a blended family (two sons of my own from a previous relationship, gaurdianship over my niece; he has a son from a previous relationship)

Our family has always been stable, my family accepted his son as their own as well (i.e grandson, nephew etc...) which is how it should be.

my s/o decides to go to his mothers house to visit, which i support ofcourse its not a monster in law situation at all.

Since we have a house of 4 kids, i suggested that he take two of our sons & i would stay back with my niece & son so, that its not a lot on me or him & its even so it works...

Nooooo it did not.

he started making up all these excuses why he didn't want to bring two of em' with him, he just wanted to bring his biological son with him & i should stay home with our other 3.

i was shocked & confused as to why...because this has never been an issue...

He then started making it look like his mother was the problem & he didn't want her to get upset at him that he brought two kids with him to visit her after not seeing her for a while...

So, i then asked why he thought she'd be like that...he then changed his story to say our son (his biological child) would not pay attention to his parents becos he'd be to busy playing with his brother...

Then it changed again to him not being comfortable bringing two of our kids in general...

& honestly there were like 3 other excuses but it was the same run around.

we have never had this problem...we're a family & i make sure that my son (step) is included in everything family related on my side from grandparents to sisters to cousins...he calls my mother nannie (how we say grandma) & my dad Pompom (how we say grandpa) like theres no treating any child different in our household.

they're all brothers & they act like it too & if you say different they will politely correct you. My s/o father is the same way they all call him abuelo & so on...

i never thought it was a big deal until he started saying all these excuses and all that...so i said forget it, you don't have to bring anyone except our son because at this point this argument is pointless & uncalled for.

so now we're not talking & im upset   because of it all & its just crazy that to me we are a family, blended, but a family nonetheless & to think or even feel that our sons & niece will be left of events on his side of the family makes my heart break cause our kids are 6, 6, 6 & 7 & they have sense and they aren't blind. My deepest fear is that they're going to feel left out or not included in family functions; and i say that because my s/o's brothers (step) birthday just past & they're going to celebrate it either this weekend or next & in the "Argument" he mentioned that it was only him & my son (step) that was going to attend...I have no idea where this is coming from...but this is definetly a problem in my eyes...

This situation is new and ridiculous to me cause i would never exclude my s/o or my son (step) out of family functions, like that doesn't even feel right or normal to me...but i guess this is just how think/feel & obviously my mind state on "family" is incorrect.

does anyone have any experience with being a blended family & how to handle these things?

Am I wrong to feel this way?

im so confused. 😔😞