I don’t know what to tell my kids

I’m getting married to my bf soon, and instead of being happy, I have been overthinking everything.

So here’s the situation:

Me (f27): metgayeret from a very religious Muslim Arab background. Dad is a Shiekh and we are no longer in contact. My mom and I are very close but that came with a very heavy price. Sister is an atheist, brother is a traditional-religious Muslim.

My partner (m26): half Israeli half European. Israeli side is super secular and not very fond of religious people. European side is vehemently against religion/theism.

Me and my partner are Orthodox Jews and we would like to raise our kids this way. The problem is, how on earth would we navigate this? For example, despite being insanely anti-religion, Christmas is huge for the European side and everyone in the family HAS to attend and be present and I’m totally against that. My mother keeps saying that she will teach my kids Islam “as a joke”, I can’t even trust my mother in law with kashrut since she was cooking pork for my bf as a child.

How would we navigate this without isolating our kids and “offend” our family members?

And more importantly, what should I tell my kids? When they ask me why is everyone different? Why is their grandmother a Muslim? “Are we Arabs or Jews?”

For context: my bf is on the same page as me.