Is he Muslim, too? Is the same true of his family? Fear of the unknown and fear one’s personal beliefs (their core being) are under attack are amazing motivators for “violence”. It’s a little late to stay in the Broom Closet but I’ve found when someone believes something so strongly (no matter the belief) it’s best to not flaunt what you believe in front of them.
You’ve asked before about being Muslim and Wiccan at the same time. It’s possible to be Wiccan and have beliefs and rituals from Islam. It’s not possible the other way around.
As you have already stated, Islam is against idols. Some branches are against images of people and animals, too. Idols of the Goddess in the home are a great way to invite fear in your husband and his family. Please be careful. I don’t want you to be scared but I do want you to be wise in how you proceed.
As for his concerns about magic being cast on him or you zapping him,
I come from an extreme version of Christianity but what I said in that quote is true for less extreme forms of all faiths. Dark magic doesn’t exist. And even if it did, it would be useless against a follower of The Divine no matter how they understand “it”.
It looks like your question about crystal grids has been answered but your other topic within this one about his concerns needed addressed. I hope this helps.